The data on residence 1 year ago were derived from answers to Question 14a, 14b, and 14c, which were asked of the population 1 year and older. For the American Community Survey, people who had moved from another residence in the United States or Puerto Rico 1 year earlier were asked to report the exact address (number and street name); the name of the city, town, or post office; the name of the U.S. county or municipio in Puerto Rico; state or Puerto Rico; and the ZIP Code where they lived 1 year ago. People living outside the United States and Puerto Rico were asked to report the name of the foreign country or U.S. Island Area where they were living 1 year ago.
For the Puerto Rico Community Survey, people who moved from another residence in Puerto Rico or the United States 1 year ago were asked to report the exact address, including the development or condominium name; the name of the city, town, or post office; the municipio in Puerto Rico (county equivalent) or county in the U.S.; and the ZIP Code where they lived. People living outside Puerto Rico and the United States were asked to report the name of the foreign country or U.S. Island Area where they were living 1 year ago.
Residence 1 year ago is used in conjunction with location of current residence to determine the extent of residential mobility of the population and the resulting redistribution of the population across the various states, metropolitan areas, and regions of the country.
When no information on previous residence was reported for a person, information for other family members, if available, was used to assign a location of residence 1 year ago. All cases of nonresponse or incomplete response that were not assigned a previous residence based on information from other family members were allocated the previous residence of another person with similar characteristics who provided complete information.
The tabulation category, "Same house," includes all people 1 year and over who did not move during the 1 year as well as those who had moved and returned to their residence 1 year ago. The category, "Different house in the United States" includes people who lived in the United States 1 year ago but in a different house or apartment from the one they occupied at the time of interview. These movers are then further subdivided according to the type of move.
In most tabulations, movers within the U.S. are divided into three groups according to their previous residence: "Different house, same county," "Different county, same state," and "Different state." The last group may be further subdivided into region of residence 1 year ago. An additional category, "Abroad," includes those whose previous residence was in a foreign country, Puerto Rico, American Samoa, Guam, the Northern Marianas, or the U.S. Virgin Islands, including members of the Armed Forces and their dependents. Some tabulations show movers who were residing in Puerto Rico or one of the U.S. Island Areas 1 year ago separately from those residing in foreign countries.
In most tabulations, movers within Puerto Rico are divided into two groups according to their residence 1 year ago: "Same municipio," and "Different municipio." Municipio of previous residence in Puerto Rico is not available for people living in the United States in 2005. Other tabulations show movers within or between metropolitan areas similar to the stateside tabulations.

The characteristics of movers may be shown using either current residence-based or previous residence-based geography. If you are interested in the number and characteristics of movers living in a specific area, you should use the standard (residence-based) tables. If you are interested in the number and characteristics of movers who previous residence was in a specific area, you should use the residence-1-year-ago-based tables. Because residence-1-year-ago information for movers cannot always be specified below the place level, the previous residence-based tables are presented only for selected geographic areas.

Beginning in 2006, the group quarters (GQ) population is included in the ACS. Some types of GQ populations have residence one year ago (migration) distributions that are different from the household population. The inclusion of the GQ population could therefore have a noticeable impact on the residence one year ago (migration) distribution. This is particularly true for areas with a substantial GQ population.

The 1996-1998 questions asked about residence 5 years ago. Beginning in 1999, the time period was changed to that of 1 year ago, which reflects the on-going data collection on the American Community Survey, and allows for annual estimates of migration. Beginning in 1999, a separate write-in line and a skip instruction were added for a foreign country response. This write-in line was moved to the mobility screener. The migration parts (city, county, and state response areas) were also reordered. Beginning in 2003, the numerical order was changed so that part c of this question would not be displayed in a separate column of the questionnaire.

Metropolitan statistical areas (MSAs) are metropolitan areas (MAs) that are not closely associated with other MAs. These areas typically are surrounded by nonmetropolitan counties (county subdivisions in New England).

The U.S. Census Bureau treats the Commonwealth of Puerto Rico as the statistical equivalent of a state for data presentation purposes. Each state and statistically equivalent entity is assigned a two-digit Federal Information Processing Standards (FIPS) code in alphabetical order by state name, followed in alphabetical order by Puerto Rico and the Island Areas. Each state and statistically equivalent entity also is assigned the two-letter FIPS/U.S. Postal Service code.

The primary legal divisions of Puerto Rico are termed "municipios." For data presentation purposes, the U.S. Census Bureau treats a municipio as the equivalent of a county in the United States.

Each municipio is assigned a unique three-digit Federal Information Processing Standards (FIPS) code in alphabetical order within Puerto Rico.

Each person is asked whether he or she was born in or outside of the United States. Those born in the United States are then asked to report the name of the state; people born elsewhere are asked to report the name of the country, or Puerto Rico and U.S. Island Areas.

The responses to this question are used to determine the U.S. citizen and non- U.S. citizen populations and native and foreign-born populations. The foreign-born population includes anyone who was not a U.S. citizen at birth. This includes people who indicate that they are not U.S. citizens, or are citizens by naturalization.

All respondents born outside of the country are asked for the year in which they came to live in the United States, including people born in Puerto Rico and U.S. Island Areas, those born abroad of an American (U.S. citizen) parent(s), and foreign-born people.

People are classified as enrolled in school if they have attended a regular public or private school or college at any time during the 3 months prior to the time of interview. This question includes instructions to "include only nursery or preschool, kindergarten, elementary school, and schooling which leads to a high school diploma, or a college degree" as a regular school or college. Data are tabulated for people 3 years and older.

Educational attainment data are tabulated for people 18 years and older. Respondents are classified according to the highest degree or the highest level of school completed. The question includes instructions for people currently enrolled in school to report the level of the previous grade attended or the highest degree received.

Ancestry refers to a person's ethnic origin or descent, roots or heritage, place of birth, or place of parents ancestors before their arrival in the United States. Some ethnic identities, such as "Egyptian" or "Polish" can be traced to geographic areas outside the United States, while other ethnicities such as "Pennsylvania German" or "Cajun" evolved within the United States.

Respondents are instructed to mark "Yes" if they sometimes or always speak a language other than English at home, but "No" if the language is spoken only at school or is limited to a few expressions or slang. Respondents are asked the name of the non- English language spoken at home. If the person speaks more than one language other than English at home, the person should report the language spoken most often or, if he or she cannot determine the one spoken most often, the language learned first.

Ability to speak English is based on the persons self-response.

Residence 1 year ago is used in conjunction with location of current residence to determine the extent of residential mobility and the resulting redistribution of the population across geographic areas of the country.

Disability is defined as a long-lasting sensory, physical, mental, or emotional condition that makes it difficult for a person to perform activities such as walking, climbing stairs, dressing, bathing, learning, or remembering. It may impede a person from being able to go outside of the home alone or work at a job or business; the definition includes people with severe vision or hearing impairments.

This question asks if the person has given birth in the previous 12 months.

An urban cluster (UC) consists of densely settled territory that has at least 2,500 people but fewer than 50,000 people. (A UC can have 50,000 or more people if fewer than 35,000 people live in an area that is not part of a military reservation.)

The U.S. Census Bureau introduced the UC for Census 2000 to provide a more consistent and accurate measure of the population concentration in and around places. UCs replace the provision in the 1990 and previous censuses that defined as urban only those places with 2,500 or more people located outside of urbanized areas.

A central place functions as the dominant center of a UC. The U.S. Census Bureau identifies one or more central places for a UC, with a preference for the most populous incorporated place(s). (Some UCs do not have a central place.)

The title of a UC may contain up to three incorporated place names, and will include the two-letter U.S. Postal Service abbreviation for each state into which the UC extends. However, if the UC does not contain an incorporated place, the UC title will include the single name of the geographic entity that occurs first from the following list: census designated place (CDP), minor civil division (MCD), or populated place recognized by the U.S. Geological Survey.

Each UC is assigned a five-digit census code in alphabetical sequence on a nationwide basis. The alphabetic assignment of codes for urban areas includes both urbanized areas (UAs) and UCs. A separate flag is included in data tabulation files to differentiate between UAs and UCs. In printed reports, this differentiation is included in the name.

An urbanized area (UA) consists of densely settled territory that contains 50,000 or more people. The U.S. Census Bureau delineates UAs to provide a better separation of urban and rural territory, population, and housing in the vicinity of large places. At least 35,000 people in a UA must live in an area that is not part of a military reservation. For Census 2000, the UA criteria specify that the delineations be performed using a zero-based approach. Because of the more stringent density requirements and the less restrictive extended place criteria, some territory that was classified as urbanized for the 1990 census has been reclassified as rural. (Area that was part of a 1990 UA has not been automatically grandfathered into the 2000 UA.) In addition, some areas that were identified as UAs for the 1990 census have been reclassified as urban clusters.

The UA central place is an incorporated place or a census designated place (CDP) with the most population within the UA. Additional place(s) may become UA central places provided that:

The places population within the UA exceeds 50,000 people; or
The places population size is at least 2/3 of the most populous UA central place.

The title of a UA may contain up to three incorporated place names, and will include the two-letter U.S. Postal Service abbreviation for each state into which the UA extends. However, if the UA does not contain an incorporated place, the UA title will include the single name of the geographic entity that occurs first from the following list: census designated place (CDP), minor civil division (MCD), or populated place recognized by the U.S. Geological Survey.

Each UA is assigned a five-digit census code in alphabetical sequence on a nationwide basis, interspersed with the codes for urban clusters (UCs), also in alphabetical sequence. For the 1990 census, the U.S. Census Bureau assigned a four-digit UA code based on the metropolitan area codes. For Census 2000, a separate flag is included in data tabulation files to differentiate between UAs and UCs. In printed reports, this differentiation is included in the name.

As a result of the urbanized area (UA) and urban cluster (UC) delineations, an incorporated place or census designated place may be partially within and partially outside of a UA or UC. Any place that is split by a UA or UC is referred to as an extended place.

For the 1990 and previous censuses, extended places were called extended cities. An extended city had to contain either 25 percent of the total land area or at least 25 square miles with an overall population density lower than 100 people per square mile. Such pieces of territory had to cover at least 5 square miles. This low-density area was classified as rural and the other, more densely settled portion of the incorporated place was classified as urban. For the 1970 and 1980 censuses, the U.S. Census Bureau identified extended cities only within UAs. For the 1990 census, the U.S. Census Bureau also applied this classification to qualifying incorporated places located outside UAs.
Documentation of the UA, UC, and extended place criteria is available from the Geographic Areas Branch, Geography Division, U.S. Census Bureau, Washington, DC 20233-7400; telephone 301-457-1099.

Data on place of work refer to the location (street address, city/county, state) at which workers carried out their occupational activities during the reference week.

Information on industry relates to the kind of business conducted by a person's employing organization; occupation describes the kind of work the person does. For employed people, the data refer to the person's job during the previous week. For those who work two or more jobs, the data refer to the job where the person worked the greatest number of hours. For unemployed people, the data refer to their last job. The information on class of worker refers to the same job as a respondents industry and occupation, and categorizes people according to the type of ownership of the employing organization.

"Total income" is the sum of the amounts reported separately for wage or salary income; net self-employment income; interest, dividends, or net rental or royalty income, or income from estates and trusts; social security or railroad retirement income; Supplemental Security Income; public assistance or welfare payments; retirement, survivor, or disability pensions; and all other income. The estimates are inflation-adjusted using the Consumer Price Index.