The data on residence 5 years earlier were derived from answers to long-form questionnaire Item 15, which was asked of a sample of the population 5 years old and over. This question asked for the state (or foreign country), U.S. county, city or town, and ZIP Code of residence on April 1, 1995, for those people who reported that on that date they lived in a different house than their current residence. Residence 5 years earlier 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.

On the Puerto Rico questionnaire, people living in Puerto Rico in 1995 were asked to report the name of the municipio (county equivalent); the city, town or village; and the ZIP Code where they lived. People living in the United States in 1995 were asked to report the name of the city, county, state, and ZIP Code where they lived. People living outside Puerto Rico or the United States were asked to report the name of the foreign country or U.S. Island Area where they were living in 1995.

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 in 1995. All cases of nonresponse or incomplete response that were not assigned a previous residence based on information from other family members were imputed the previous residence of another person with similar characteristics who provided complete information on residence 5 years earlier.

The tabulation category, "Same house," includes all people 5 years old and over who did not move during the 5 years as well as those who had moved but by Census Day had returned to their 1995 residence. The category, "Different house in the United States," includes people who lived in the United States 5 years earlier but lived in a different house or apartment from the one they occupied on Census Day. 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 in 1995. An additional category, "Abroad," includes those whose previous residence was in a foreign country, Puerto Rico, American Samoa, Guam, the Commonwealth of the Northern Mariana Islands, 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 in 1995 separately from those residing in foreign countries.

In most tabulations, movers within Puerto Rico are divided into two groups according to their 1995 residence: "Same municipio," and "Different municipio." Municipio of previous residence in Puerto Rico is not available for people living in the United States in 2000. Other tabulations show movers within or between metropolitan areas similar to the stateside tabulations.

Some special tabulations present data on inmigrants, outmigrants, and net migration. "Inmigrants" are generally defined as those people who moved into an area. In some tabulations, movers from abroad may be included in the number of inmigrants; in others, only movers within the United States are included. "Outmigrants" are people who moved out of a specific area to some other place in the United States. Movers who left the United States are not available to be included in any tabulations. "Net migration" is calculated by subtracting the number of outmigrants from the number of inmigrants. The net migration for the area is net inmigration if the result is positive and net outmigration if the result is negative. In the tabulations, net outmigration is indicated by a minus sign (-).

Inmigrants and outmigrants for states include only those people who did not live in the same state at both dates; that is, they exclude people who moved between counties within the same state. Thus, the sum of the inmigrants to (or outmigrants from) all counties in any state is greater than the number of inmigrants to (or outmigrants from) that state. However, in the case of net migration, the sum of the nets for all the counties within a state equals the net for the state. In the same fashion, the net migration for a division or region equals the sum of the nets for the states comprising that division or region, while the number of inmigrants and outmigrants for that division or region is less than the sum of the inmigrants or outmigrants for the individual states.

The number of people who were living in a different house 5 years earlier is somewhat less than the total number of moves during the 5-year period. Some people in the same house at the two dates had moved during the 5-year period but by the time of the census had returned to their 1995 residence. Other people who were living in a different house had made one or more intermediate moves. For similar reasons, the number of people living in a different county, metropolitan area, or state, or the number moving between nonmetropolitan areas, may be understated.

States are the primary governmental divisions of the United States. The District of Columbia is treated as a statistical equivalent of a state for data presentation purposes. For Census 2000, the U.S. Census Bureau also treats a number of entities that are not legal divisions of the United States as statistically equivalent to a state: American Samoa, the Commonwealth of the Northern Mariana Islands, Guam, Puerto Rico, and the Virgin Islands of the United States.

Each state and statistically equivalent entity is assigned a two-digit numeric 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 a two-letter FIPS/U.S. Postal Service code and a two-digit census code. The census code is assigned on the basis of the geographic sequence of each state within each census division; the first digit of the code identifies the respective division, except for Puerto Rico and the Island Areas, which are not assigned to any region or division. The census regions, census divisions, and their component states are listed in Figure A-3.

The primary legal divisions of most states are termed "counties." In Louisiana, these divisions are known as parishes. In Alaska, which has no counties, the statistically equivalent entities are census areas, city and boroughs (as in Juneau City and Borough), a municipality (Anchorage), and organized boroughs. Census areas are delineated cooperatively for data presentation purposes by the state of Alaska and the U.S. Census Bureau. In four states (Maryland, Missouri, Nevada, and Virginia), there are one or more incorporated places that are independent of any county organization and thus constitute primary divisions of their states; these incorporated places are known as "independent cities" and are treated as equivalent to counties for data presentation purposes. (In some data presentations, they may be treated as county subdivisions and places.) The District of Columbia has no primary divisions, and the entire area is considered equivalent to a county for data presentation purposes. In American Samoa, the primary divisions are districts and islands; in the Northern Mariana Islands, municipalities; in the Virgin Islands of the United States, the principal islands of St. Croix, St. John, and St. Thomas. Guam has no primary divisions, and the entire area is considered equivalent to a county for data presentation purposes.

Each county and statistically equivalent entity is assigned a three-digit Federal Information Processing Standards code that is unique within state. These codes are assigned in alphabetical order of county or county equivalent within state, except for the independent cities, which are assigned codes higher than and following the listing of counties.

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.