Notes: One method used by demographers to measure the relative number of males and females in a population is the sex ratio. The male-to-female sex ratio is calculated by dividing the number of males (of all ages) by the number of females (of all ages) and multiplying by 100. A value above 100 means there are more males than females in the population. For example, a sex ratio of 117 means there are 117 males to every 100 females. A value below 100 indicates more females than males. A sex ratio of 84 means there are 84 males to every 100 females. A sex ratio of 100 means there are an equal number of males and females (i.e., 100 males to 100 females).

In 2010, the male-to-female sex ratio among the native-born population was 97 males to 100 females, which was similar to the ratio among immigrants (96 males to 100 females).

In censuses of 1880, 1890, and 1910 to 1940, published census data on the age and sex distribution of the foreign-born population were limited primarily to the foreign-born White population. During this period, the foreign-born population of races other than White, which peaked at 220,744 in 1930, represented between 1 percent and 2 percent of the total foreign-born population. Because age data for the total foreign-born population are available for 1870, 1900, and 1950 to 1990, and because the foreign-born population of races other than White represented such a small proportion of the total foreign-born population from 1880 to 1940, the population universe for this table is the total foreign-born population. The foreign-born population of races other than White is included in the category "age data not available" for 1880, 1890, and 1910 to 1940.

Source: The 2010 data are from the US Census Bureau's 2010 American Community Survey. The 2000 data are from the Current Population Survey, March Supplement, 2000. All other data are from Gibson, Campbell and Emily Lennon, US Census Bureau, Working Paper No. 29, Historical Census Statistics on the Foreign-Born Population of the United States: 1850 to 1990, US Government Printing Office, Washington, DC. 1999. This report is available online.