A household is considered to be cost-burdened if more than 30 percent of household income is going toward housing costs (gross rent or monthly owner costs). Gross rent as a percentage of household income in 1999 is a computed ratio of monthly gross rent to monthly household income (total household income in 1999 divided by 12). Units for which no cash rent is paid and units occupied by households that reported no income or a net loss in 1999 were not included in the calculations. The information on selected monthly owner costs as a percentage of household income in 1999 is the computed ratio of selected monthly owner costs to monthly household income in 1999.

Census 2000 data on disability status were derived from answers to long-form questionnaire Items 16 and 17. Item 16 was a two-part question that asked about the existence of the following long-lasting conditions: (a) blindness, deafness, or a severe vision or hearing impairment (sensory disability) and (b) a condition that substantially limits one or more basic physical activities, such as walking, climbing stairs, reaching, lifting, or carrying (physical disability). Item 16 was asked of a sample of the population 5 years old and over. Item 17 was a four-part question that asked if the individual had a physical, mental, or emotional condition lasting 6 months or more that made it difficult to perform certain activities. The four activity categories were: (a) learning, remembering, or concentrating (mental disability); (b) dressing, bathing, or getting around inside the home (self-care disability); (c) going outside the home alone to shop or visit a doctor's office (going outside the home disability); and (d) working at a job or business (employment disability). Individuals were classified as having a disability if any of the following three conditions were true: (1) they were 5 years old and over and had a response of "yes" to a sensory, physical, mental or self-care disability; (2) they were 16 years old and over and had a response of ''yes'' to going outside the home disability; or (3) they were 16 to 64 years old and had a response of "yes" to employment disability. The 1990 census data products did not include a general disability status indicator.

A family includes a householder and one or more other people living in the same household who are related to the householder by birth, marriage, or adoption. All people in a household who are related to the householder are regarded as members of his or her family. A family household may contain people not related to the householder, but those people are not included as part of the householder's family in census tabulations. Thus, the number of family households is equal to the number of families, but family households may include more members than do families. A household can contain only one family for purposes of census tabulations. Not all households contain families since a household may be comprised of a group of unrelated people or of one person living alone. Families are classified by type as either a "married-couple family" or "other family" according to the presence of a spouse. "Other family" is further broken out according to the sex of the householder. A married-couple family includes a family in which the householder and his or her spouse are enumerated as members of the same household. Other family: Male householder, no wife present includes a family with a male maintaining a household with no wife of the householder present. Other family: Female householder, no husband present includes a family with a female maintaining a household with no husband of the householder present. Non-family household includes a householder living alone or with non-relatives only.

Gross rent is the contract rent plus the estimated average monthly cost of utilities (electricity, gas, water and sewer) and fuels (oil, coal, kerosene, wood, etc.) if these are paid by the renter (or paid for the renter by someone else). Gross rent is intended to eliminate differentials that result from varying practices with respect to the inclusion of utilities and fuels as part of the rental payment. The estimated costs of utilities and fuels are reported on an annual basis but are converted to monthly figures for the tabulations. Only renter units paying cash rent are included. Median gross rent divides the gross rent distribution into two equal parts: one-half of the cases falling below the median gross rent and one-half above the median. Median gross rent is rounded to the nearest whole dollar. Specified renter-occupied units exclude 1-family houses on 10 acres or more. Units not paying cash rent are generally provided free by friends or relatives or in exchange for services, such as resident manager, caretaker, minister, or tenant farmer. Housing units on military bases also are classified in the "No cash rent" category. "Rented for cash rent" includes units in continuing care, sometimes called life care arrangements. These arrangements usually involve a contract between one or more individuals and a service provider guaranteeing the individual shelter, usually a house or apartment, and services, such as meals or transportation to shopping or recreation.

A household (also referred to as 'occupied housing units') includes all of the people who occupy a housing unit. (People not living in households are classified as living in group quarters.) A housing unit is a house, an apartment, a mobile home, a group of rooms, or a single room occupied (or if vacant, intended for occupancy) as separate living quarters. Separate living quarters are those in which the occupants live separately from any other people in the building and that have direct access from the outside of the building or through a common hall. The occupants may be a single family, one person living alone, two or more families living together, or any other group of related or unrelated people who share living quarters. One person in each household is designated as the householder. In most cases, the householder is the person, or one of the people, in whose name the home is owned, being bought, or rented. If there is no such person in the household, any adult household member 15 years old and over could be designated as the householder. Households are classified by type according to the sex of the householder and the presence of relatives. Two types of householders are distinguished: family householders and non-family householders. A family householder is a householder living with one or more individuals related to him or her by birth, marriage, or adoption. The householder and all of the people in the household related to him or her are family members. A non-family householder is a householder living alone or with non-relatives only.

The future demand for housing will be affected largely by the changing age structure within the state along with current migration patterns. Therefore, in order to assess future demand for housing, we developed a forecast of households by age for the next 10 years. These projections were calculated in a two-step process. First, an age-specific distribution of householders was calculated using 2000 Census data. The stability of this distribution was evaluated by cross-checking the age-specific proportions with 1990 Census data. In general, the relationship between the number of persons in a specific age group and the proportion of householders in that age group remained fairly constant over the two time periods. We assumed, therefore, this relationship would hold for the next 10 years. Thus, in the second step we applied these coefficients to age-specific population projections developed by the North Dakota State Data Center and published in 2002.

A second area of housing demand that needs to be monitored is tied to shifts in the income of households. In order to explore these changes, we developed a forecast of households by income. This was accomplished through a three-step procedure. First, the distribution of household income by age of householder was calculated for the six broad income categories using data from Census 2000. The income categories, based on median family income (MFI) using the 2000 Census, were: Extremely-Low Income (0 to 30 percent MFI) = less than $15,000; Low Income (31 percent to 50 percent MFI) = $15,000 to $24,999; Tax Credit (51 percent to 60 percent MFI) = $25,000 to $34,999; Moderate (51 percent to 80 percent MFI) = $25,000 to $49,999; Middle Income (81 percent to 115 percent MFI) = $50,000 to $74,999; and Upper Income (above 115 percent MFI) = $75,000 or more. These categories were selected to align with various housing support programs. Second, the usefulness of utilizing proportional assignment of income to householders by age for the purpose of forecasting was assessed by cross-checking the distributions found in 2000 against the corresponding age-specific income distributions found in the 1990 Census. The value of using proportional assignment to MFI is that it eliminates the need to project actual future income levels and associated inflation. Instead, the forecast focuses on changes in the distribution of households relative to MFI. Similar proportions of age-specific households were found in each income category related to MFI, thus it was assumed that these proportions would hold throughout the projection period. The final step was to apply the age- and income-specific proportions based on 2000 Census data to the total projected number of households by age.

Demand for housing by type of homebuyer was projected as well. Modeling for this forecast was very similar to that used to project household income in that proportional allocation was used. Five types of homebuyers were classified based on historical profiles of these homebuyers. The first-time homebuyer was assumed to be under the age of 35 and have a household income between $25,000 and $74,999 (based on the dollar value in 2000). Low-income homebuyers were assumed to be younger than 75 years of age and have a household income less than $25,000 (based on the dollar value in 2000). Moderate-income homebuyers were assumed to be between the ages of 35 and 74 and have a household income between $25,000 and $49,999 (based on the dollar value in 2000). Upscale homebuyers were assumed to be between the ages of 35 and 74 and have a household income of $75,000 or more (based on the dollar value in 2000). Finally, elderly homebuyers were classified as any homebuyer ages 75 or older.

Finally, projections of housing by tenure were based on the assumption that historical patterns of home ownership are good predictors of future trends. Age-specific distributions of home ownership and rental-occupied housing were calculated for each geography (e.g. region, county, city, and reservation) based on Census 2000. The stability of these distributions was evaluated by comparing them to corresponding distributions for 1990. In general, the pattern of owner-occupied and rental-occupied units for each age category was very similar for the two time periods. Therefore, we assumed the age-specific proportions of owner- and renter-occupied units relative to total occupied housing units would hold throughout the projection period. We applied the 2000 age-specific distributions of owner- and renter-occupied housing units to our projections of total occupied housing units to make our forecast of housing by tenure.

In order to evaluate the relationship between future demand for housing and what housing might be available (i.e., supply), two housing supply forecasts were developed. The first model (Model 1) presents a scenario of what housing supply would be if the trend in housing construction over the past 10 years (i.e.; 1993 to 2003 for state, cities, counties, and planning regions; and 1990 to 2000 for reservation areas) were to continue unabated through the year 2015. This was accomplished by calculating the average annual change in housing over the last decade and applying that rate of change annually to the existing housing stock for each successive year until 2015. The purpose of this approach is to provide decision makers a benchmark for evaluating the appropriateness of continuing the existing level of housing construction. One needs to keep in mind that this is a linear projection. Thus, if housing construction was in decline during the past ten years, this model will assume that housing construction should continue to decline for the next ten years regardless of population projections. The second housing supply forecast (Model 2) projects future housing units based on the growth or decline in future households. Thus, this forecast predicts changes in housing supply based on shifts in an area's population profile. In particular, it relies on the projection of households and the historical relationship between households and available housing units. In brief, it assumes that the way the market historically responded to changes in the number of households, through the supply of new housing units, should be similar to how the market will respond in the future. Therefore, this forecast is based on the ratio of households (i.e., occupied housing units) to total housing units.

A housing unit may be a house, an apartment, a mobile home, a group of rooms, or a single room that is occupied (or, if vacant, is intended for occupancy) as separate living quarters. Separate living quarters are those in which the occupants live separately from any other individuals in the building and which have direct access from outside the building or through a common hall. For vacant units, the criteria of separateness and direct access are applied to the intended occupants whenever possible. If that information cannot be obtained, the criteria are applied to the previous occupants. Both occupied and vacant housing units are included in the housing unit inventory. Boats, recreational vehicles (RVs), vans, tents, and the like are housing units only if they are occupied as someone's usual place of residence. Vacant mobile homes are included provided they are intended for occupancy on the site where they stand. Vacant mobile homes on dealers' lots, at the factory, or in storage yards are excluded from the housing inventory. Also excluded from the housing inventory are quarters being used entirely for nonresidential purposes, such as a store or an office, or quarters used for the storage of business supplies or inventory, machinery, or agricultural products.

A unit has complete kitchen facilities when it has all of the following:
(1) a sink with piped water;
(2) a range, or cook top and oven; and
(3) a refrigerator.
All kitchen facilities must be located in the house, apartment, or mobile home, but they need not be in the same room. A housing unit having only a microwave or portable heating equipment, such as a hot plate or camping stove, should not be considered as having complete kitchen facilities. An ice box is not considered to be a refrigerator.

Fiscal Year 2004 Median Family Incomes (MFI) are calculated by the U.S. Department of Housing and Urban Development (HUD). These estimates are based on 2000 Census data on family incomes and are updated to 2004 using a combination of Bureau of Labor Statistics (BLS) data, Census American Community Survey (ACS) state data, and Census Current Population Survey (CPS) data. For a detailed description of the methodology used in calculating these numbers, visit: http://www.huduser.org/datasets/il/IL04Est/index.html

See Median Family Income (MFI) for Fiscal Year 2004 definition.

See Net Migration.

"Mortgage" refers to all forms of debt where the property is pledged as security for repayment of the debt, including deeds of trust; trust deeds; contracts to purchase; land contracts; junior mortgages; and home equity loans. The category ''not mortgaged'' is comprised of housing units owned free and clear of debt.

Refers to situations where data are not available or the calculation is not applicable.

Migration is the movement of people into and out of a specific geography. Net migration is the difference between those moving into a specific geography and those moving out. For example, between 2000 and 2003, North Dakota had a net out-migration of 13,288 persons. This means that 13,288 more persons moved out of North Dakota than moved in. Migration is one of three components to population change, the other two being births and deaths.

A housing unit is classified as occupied if it is the usual place of residence of the person or group of people living in it, or if the occupants are only temporarily absent; that is, away on vacation or a business trip. The occupants may be a single family, one person living alone, two or more families living together, or any other group of related or unrelated people who share living quarters. Occupied rooms or suites of rooms in hotels, motels, and similar places are classified as housing units only when occupied by permanent residents; that is, people who consider the hotel as their usual place of residence or have no usual place of residence elsewhere. If any of the occupants in rooming or boarding houses, congregate housing, or continuing care facilities live separately from others in the building and have direct access, their quarters are classified as separate housing units. The living quarters occupied by staff personnel within any group quarters are separate housing units if they satisfy the housing unit criteria of separateness and direct access; otherwise, they are considered group quarters.

Occupants per room is obtained by dividing the number of people in each occupied housing unit by the number of rooms in the unit. The figures show the number of occupied housing units having the specified ratio of people per room. Although the Census Bureau has no official definition of crowded units, many users consider units with more than one occupant per room to be crowded.

Population refers to the total number of residents in the specified geography. County population projections were developed using a standard cohort-survival model. Population projections for cities were calculated based on the assumption that the percentage they comprise of the overall county population will stay consistent. Population projections for reservation areas were based on the assumption that the age distributions will stay consistent. All models were based on census trends that reflect downward movement among most rural areas and upward growth among the larger urban centers.

The Census Bureau uses the federal government's official poverty definition. The Social Security Administration (SSA) developed the original poverty definition in 1964, which federal interagency committees subsequently revised in 1969 and 1980. The Office of Management and Budget's (OMB's) Directive 14 prescribes this definition as the official poverty measure for federal agencies to use in their statistical work.

Derivation of the Current Poverty Measure
When the Social Security Administration (SSA) created the poverty definition in 1964, it focused on family food consumption. The U.S. Department of Agriculture (USDA) used its data about the nutritional needs of children and adults to construct food plans for families. Within each food plan, dollar amounts varied according to the total number of people in the family and the family's composition, such as the number of children within each family. The cheapest of these plans, the Economy Food Plan, was designed to address the dietary needs of families on an austere budget. Since the USDA's 1955 Food Consumption Survey showed that families of three or more people across all income levels spent roughly one-third of their income on food, the SSA multiplied the cost of the Economy Food Plan by three to obtain dollar figures for the poverty thresholds. Since the Economy Food Plan budgets varied by family size and composition, so too did the poverty thresholds. For 2-person families, the thresholds were adjusted by slightly higher factors because those households had higher fixed costs. Thresholds for unrelated individuals were calculated as a fixed proportion of the corresponding thresholds for 2-person families. The poverty thresholds are revised annually to allow for changes in the cost of living as reflected in the Consumer Price Index (CPI-U). The poverty thresholds are the same for all parts of the country - they are not adjusted for regional, state or local variations in the cost of living. For a detailed discussion of the poverty definition, see U.S. Census Bureau, Current Population Reports, ''Poverty in the United States: 1999,'' P-60-210.

How Poverty Status is Determined
The poverty status of families and unrelated individuals in 1999 was determined using 48 thresholds (income cutoffs) arranged in a two dimensional matrix. The matrix consists of family size (from 1 person to 9 or more people) cross-classified by presence and number of family members under 18 years old (from no children present to 8 or more children present). Unrelated individuals and 2-person families were further differentiated by the age of the reference person (under 65 years old and 65 years old and over).
To determine a person's poverty status, one compares the person's total family income with the poverty threshold appropriate for that person's family size and composition (see table below). If the total income of that person's family is less than the threshold appropriate for that family, then the person is considered poor, together with every member of his or her family. If a person is not living with anyone related by birth, marriage, or adoption, then the person's own income is compared with his or her poverty threshold.

Weighted average thresholds.Even though the official poverty data are based on the 48 thresholds arranged by family size and number of children within the family, data users often want to get an idea of the ''average'' threshold for a given family size. The weighted average thresholds provide that summary. They are weighted averages because for any given family size, families with a certain number of children may be more or less common than families with a different number of children. In other words, among 3-person families, there are more families with two adults and one child than families with three adults. To get the weighted average threshold for families of a particular size, multiply each threshold by the number of families for whom that threshold applies; then add up those products, and divide by the total number of families who are of that family size. For example, for 3-person families, 1999 weighted thresholds were calculated in the following way using information from the 2000 Current Population Survey:

Family Type	Number of Families	Threshold	Total
No children (three adults)	5,213	$13,032	$67,935,816
One child (two adults)	8,208	$13,410	$110,069,280
Two children (one adult)	2,656	$13,423	$35,651,488
Totals	16,077		$213,656,584

Source: Current Population Survey, March 2000.

Dividing $213,656,584 by 16,077 (the total number of 3-person families) yields $13,290, the weighted average threshold for 3-person families. Please note that the thresholds are weighted not just by the number of poor families, but by all families for which the thresholds apply: the thresholds are used to determine which families are at or above poverty, as well as below poverty.

Individuals for whom poverty status is determined. Poverty status was determined for all people except institutionalized people, people in military group quarters, people in college dormitories, and unrelated individuals under 15 years old. These groups also were excluded from the numerator and denominator when calculating poverty rates. They are considered neither "poor" nor "nonpoor".

Complete plumbing facilities include:
(1) hot and cold piped water
(2) a flush toilet, and
(3) a bathtub or shower. All three facilities must be located inside the house, apartment, or mobile home, but not necessarily in the same room. Housing units are classified as lacking complete plumbing facilities when any of the three facilities is not present.

The North Dakota State Data Center, for the purposes of the North Dakota Statewide Housing Needs Assessment study, prepared a series of projections for population, housing supply and housing demand. The projections were calculated for the following years; 2005, 2010, and 2015. Data referring to 1990 or 2000 are from the U.S. Census Bureau's decennial census. Data referring to 1993 and 2003 are estimates provided by the U.S. Census Bureau's Population Division.

The concept of race, as used by the Census Bureau, reflects self-identification by people according to the race or races with which they most closely identify. These categories are socio-political constructs and should not be interpreted as being scientific or anthropological in nature. Furthermore, the race categories include both racial and national-origin groups.

The racial classifications used by the Census Bureau adhere to the October 30, 1997, Federal Register Notice entitled, "Revisions to the Standards for the Classification of Federal Data on Race and Ethnicity," issued by the Office of Management and Budget (OMB). These standards govern the categories used to collect and present federal data on race and ethnicity. The OMB requires five minimum categories (White, Black or African American, American Indian or Alaska Native, Asian, and Native Hawaiian or Other Pacific Islander) for race. The race categories are described below with a sixth category, "Some other race," added with OMB approval. In addition to the five race groups, the OMB also states that respondents should be offered the option of selecting one or more races.

If an individual did not provide a race response, the race or races of the householder or other household members were assigned using specific rules of precedence of household relationship. For example, if race was missing for a natural-born child in the household, then either the race or races of the householder, another natural-born child, or the spouse of the householder were assigned. If race was not reported for anyone in the household, the race or races of a householder in a previously processed household were assigned.

White. A person having origins in any of the original peoples of Europe, the Middle East, or North Africa. It includes people who indicate their race as "White" or report entries such as Irish, German, Italian, Lebanese, Near Easterner, Arab, or Polish.
Black or African American. A person having origins in any of the Black racial groups of Africa. It includes people who indicate their race as "Black, African American, or Negro," or provide written entries such as African American, Afro-American, Kenyan, Nigerian, or Haitian.
American Indian or Alaska Native. A person having origins in any of the original peoples of North and South America (including Central America) and who maintain tribal affiliation or community attachment. It includes people who classified themselves as described below.
American Indian. This category includes people who indicated their race as ''American Indian,'' entered the name of an Indian tribe, or reported such entries as Canadian Indian, French American Indian, or Spanish American Indian.
Alaska Native. This category includes written responses of Eskimos, Aleuts, and Alaska Indians as well as entries such as Arctic Slope, Inupiat, Yupik, Alutiiq, Egegik, and Pribilovian.
Asian. A person having origins in any of the original peoples of the Far East, Southeast Asia, or the Indian subcontinent including, for example, Cambodia, China, India, Japan, Korea, Malaysia, Pakistan, the Philippine Islands, Thailand, and Vietnam. It includes "Asian Indian", "Chinese", "Filipino", "Korean", "Japanese", "Vietnamese", and "Other Asian".
Native Hawaiian or Other Pacific Islander. A person having origins in any of the original peoples of Hawaii, Guam, Samoa, or other Pacific Islands. It includes people who indicate their race as "Native Hawaiian", "Guamanian or Chamorro", "Samoan", and "Other Pacific Islander".
Some other race. This category includes all other responses not included in the "White", "Black or African American", "American Indian or Alaska Native", "Asian", and "Native Hawaiian or Other Pacific Islander" race categories described above. Respondents providing write-in entries such as multiracial, mixed, interracial, or a Hispanic/Latino group (for example, Mexican, Puerto Rican, or Cuban) in the "Some other race" write-in space are included in this category.
Two or more races. People may have chosen to provide two or more races either by checking two or more race response check boxes, by providing multiple write-in responses, or by some combination of check boxes and write-in responses. "Two or more races" refers to combinations of two or more of the following race categories:
1. White
2. Black or African American
3. American Indian and Alaska Native
4. Asian
5. Native Hawaiian and Other Pacific Islander
6. Some other race
There are 57 possible combinations involving the race categories shown above. Thus, according to this approach, a response of "White" and "Asian" was tallied as two or more races, while a response of "Japanese" and "Chinese" was not because "Japanese" and "Chinese" are both Asian responses.

Specified owner-occupied and specified vacant-for-sale housing units include only 1-family houses on less than 10 acres without a business or medical office on the property. The data for specified units exclude mobile homes, houses with a business or medical office, houses on 10 or more acres, and housing units in multi-unit buildings.

Specified renter-occupied and specified vacant-for-rent units exclude 1-family houses on 10 acres or more.

All occupied housing units are classified as either owner occupied or renter occupied. A housing unit is owner occupied if the owner or co-owner lives in the unit even if it is mortgaged or not fully paid for. All occupied housing units that are not owner occupied, whether they are rented for cash rent or occupied without payment of cash rent, are classified as renter occupied. Units not paying cash rent are generally provided free by friends or relatives or in exchange for services, such as resident manager, caretaker, minister, or tenant farmer. Housing units on military bases also are classified in the ''No cash rent'' category. "Rented for cash rent" includes units in continuing care, sometimes called life care arrangements. These arrangements usually involve a contract between one or more individuals and a service provider guaranteeing the individual shelter, usually a house or apartment, and services, such as meals or transportation to shopping or recreation.

The data on units in structure include both occupied and vacant housing units. A structure is a separate building that either has open spaces on all sides or is separated from other structures by dividing walls that extend from ground to roof. In determining the number of units in a structure, all housing units, both occupied and vacant, are counted. Stores and office space are excluded. The statistics are presented for the number of housing units in structures of specified type and size, not for the number of residential buildings.
1-unit, detached. This is a 1-unit structure detached from any other house; that is, with open space on all four sides. Such structures are considered detached even if they have an adjoining shed or garage. A 1-family house that contains a business is considered detached as long as the building has open space on all four sides. Mobile homes to which one or more permanent rooms have been added or built also are included.
1-unit, attached. This is a 1-unit structure that has one or more walls extending from ground to roof separating it from adjoining structures. In row houses (sometimes called townhouses), double houses, or houses attached to nonresidential structures, each house is a separate, attached structure if the dividing or common wall goes from ground to roof.
2 or more units. These are units in structures containing 2 or more housing units, further categorized as units in structures with 2, 3 or 4, 5 to 9, 10 to 19, 20 to 49, and 50 or more units.
Mobile home. Both occupied and vacant mobile homes to which no permanent rooms have been added are counted in this category. Mobile homes used only for business purposes or for extra sleeping space and mobile homes for sale on a dealer's lot, at the factory, or in storage are not counted in the housing inventory. In 1990, the category was "mobile home or trailer".
Boat, RV, van, etc. This category is for any living quarters occupied as a housing unit that does not fit in the previous categories. Examples that fit in this category are houseboats, railroad cars, campers, and vans.

Vacancy status and other characteristics of vacant units were determined by information from landlords, owners, neighbors, rental agents, and others. Vacant units are subdivided according to their housing market classification as follows:
For rent. These are vacant units offered "for rent", and vacant units offered either "for rent" or "for sale".
For sale only. These are vacant units offered "for sale only", including units in cooperatives and condominium projects if the individual units are offered "for sale only". If units are offered either "for rent" or "for sale", they are included in the "for rent" classification.
Rented or sold, not occupied. If any money rent has been paid or agreed upon but the new renter has not moved in as of the date of enumeration, or if the unit has recently been sold but the new owner has not yet moved in, the vacant unit is classified as "rented or sold, not occupied".
For seasonal, recreational, or occasional use. These are vacant units used or intended for use only in certain seasons, for weekends, or other occasional use throughout the year. Seasonal units include those used for summer or winter sports or recreation, such as beach cottages and hunting cabins. Seasonal units also may include quarters for such workers as herders and loggers. Interval ownership units, sometimes called shared-ownership or time-sharing condominiums, also are included in this category.
For migrant workers. These include vacant units intended for occupancy by migrant workers employed in farm work during the crop season. (Work in a cannery, a freezer plant, or a food-processing plant is not farm work).
Other vacant. If a vacant unit does not fall into any of the categories specified above, it is classified as "other vacant". For example, this category includes units held for occupancy by a caretaker or janitor, and units held for personal reasons of the owner.

A housing unit is vacant if no one is living in it at the time of enumeration, unless its occupants are only temporarily absent. Units temporarily occupied at the time of enumeration entirely by people who have a usual residence elsewhere are also classified as vacant. New units not yet occupied are classified as vacant housing units if construction has reached a point where all exterior windows and doors are installed and final usable floors are in place. Vacant units are excluded from the housing inventory if they are open to the elements; that is, the roof, walls, windows, and/or doors no longer protect the interior from the elements. Also excluded are vacant units with a sign that they are condemned or they are to be demolished.

Value is the respondent's estimate of how much the property (house and lot, mobile home and lot, or condominium unit) would sell for if it were for sale. If the house or mobile home was owned or being bought, but the land on which it sits was not, the respondent was asked to estimate the combined value of the house or mobile home and the land. For vacant units, value was the price asked for the property. Value was tabulated separately for all owner-occupied and vacant-for-sale housing units, owner-occupied and vacant-for-sale mobile homes, and specified owner-occupied and specified vacant-for-sale housing units. The median divides the value distribution into two equal parts: one-half of the cases falling below the median value of the property (house and lot, mobile home and lot, or condominium unit) and one-half above the median. Specified owner-occupied housing units include only 1-family houses on less than 10 acres without a business or medical office on the property. The data for "specified units" exclude mobile homes, houses with a business or medical office, houses on 10 or more acres, and housing units in multi-unit buildings.

The data on year structure built apply to both occupied and vacant housing units. Year structure built refers to when the building was first constructed, not when it was remodeled, added to, or converted. For housing units under construction that met the housing unit definition-that is, all exterior windows, doors, and final usable floors were in place-the category "1999 or 2000" was used for tabulations. For mobile homes, houseboats, RVs, etc, the manufacturer's model year was assumed to be the year built. The data relate to the number of units built during the specified periods that were still in existence at the time of enumeration.