Includes all people who have never been married, including people whose only marriage(s) was annulled.

Includes people ever married at the time of interview (including those now married, separated, widowed, or divorced).

Includes people whose current marriage has not ended through widowhood, divorce, or separation (regardless of previous marital history). The category may also include couples who live together or people in common-law marriages if they consider this category the most appropriate. In certain tabulations, currently married people are further classified as "spouse present" or "spouse absent."

Includes people legally separated or otherwise absent from their spouse because of marital discord. Those without a final divorce decree are classified as separated. This category also includes people who have been deserted or who have parted because they no longer want to live together but who have not obtained a divorce.

Includes widows and widowers who have not remarried.

Includes people who are legally divorced and who have not remarried. Those without a final divorce decree are classified as separated. In selected tabulations, data for married and separated people are reorganized and combined with information on the presence of the spouse in the same household.

All people whose current marriage has not ended by widowhood or divorce. This category includes people defined above as "separated."

• Spouse Present

Married people whose wife or husband was reported as a member of the same household or same group quarters facility, including those whose spouses may have been temporarily absent for such reasons as travel or hospitalization.

• Spouse Absent

Married people whose wife or husband was not reported as a member of the same household or the same group quarters facility.

• Separated

Defined above.

• Spouse Absent, Other

Married people whose wife or husband was not reported as a member of the same household, excluding separated. Included is any person whose spouse was employed and living away from home or in an institution or serving away from home in the Armed Forces.

Differences between the number of currently married males and the number of currently married females occur because of reporting differences and because some husbands and wives have their usual residence in different areas. By definition, the numbers would be the same.

The median age at first marriage is calculated indirectly by estimating the proportion of young people who will marry during their lifetime, calculating one-half of this proportion, and determining the age (at the time of the survey) of people at this half-way mark by osculatory interpolation. It does not represent the actual median age of the population who married during the calendar year. It is shown to the nearest tenth of a year. Henry S. Shryock and Jacob S. Siegel outline the osculatory procedure in Methods and Materials of Demography , First Edition (May 1973), Volume 1, pages 291-296.

Beginning in 2007, people 15 years and over who were ever married (currently married, widowed, separated, or divorced) were asked if they had been married, widowed, or divorced in the past 12 months. They were asked how many times (once, two times, three or more times) they have been married, and the year of their last marriage.

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

The word "current" was dropped from the 1996-1998 question. Since 1999, the question states, "What is this persons marital status?" The American Community Survey began providing the median age at first marriage with the 2004 data.

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.

The U.S. Census Bureau recognizes barrios and barrios-pueblo as the primary legal divisions of municipios. These entities are similar to the minor civil divisions (MCDs) used for reporting decennial census data in 28 states of the United States. Subbarrios in 23 municipios are the primary legal subdivisions of the barrios-pueblo and some barrios. The U.S. Census Bureau presents the same types of Census 2000 data for these "sub-MCDs" as it does for the barrios and barriospueblo. (There is no geographic entity in the United States equivalent to the subbarrio.) Each barrio, barrio-pueblo, and subbarrio is assigned a five-digit Federal Information Processing Standards (FIPS) code in alphabetical order within Puerto Rico.

There are no incorporated places in Puerto Rico; instead, the U.S. Census Bureau provides decennial census data for two types of census designated places (CDPs): (1) zonas urbanas, representing the governmental center of each municipio, and (2) comunidades, representing other settlements. For Census 2000, there are no minimum population size requirements for CDPs. (For the 1990 census, the U.S. Census Bureau had required comunidades to have at least 1,000 people.)

Each zona urbana and comunidad is assigned a five-digit Federal Information Processing Standards (FIPS) code in alphabetical order within Puerto Rico.
Some types of geographic entities do not apply in Puerto Rico. For instance, Puerto Rico is not in any census region or census division. In addition, the U.S. Census Bureau does not tabulate data for state legislative districts and traffic analysis zones in Puerto Rico. (See also Congressional District (CD).)