1980 United States census in the context of 99th United States Congress

The 1990 United States census, conducted by the Census Bureau, determined the resident population of the United States to be 248,709,873, an increase of 9.8 percent over the 226,545,805 persons enumerated during the 1980 census.

Approximately 16 percent of households received a "long form" of the 1990 census, which contained more than 100 questions. Full documentation on the 1990 census, including census forms and a procedural history, is available from the Integrated Public Use Microdata Series.

Jefferson County is located in the eastern portion of the U.S. state of Missouri. It is a part of the St. Louis Metropolitan Area. As of the 2020 census, the population was 226,739, making it the sixth-most populous county in Missouri. Its county seat is Hillsboro. The county was organized in 1818 and named in honor of former president Thomas Jefferson. In 1980, according to the U.S. census held that year, the county contained the mean center of U.S. population. Notably, this was the first census in which the center of population was west of the Mississippi River. Jefferson County is part of the St. Louis Metropolitan Statistical Area and encompasses many of the city's southern suburbs.

British Americans usually refers to Americans whose ancestral origin originates wholly or partly in the United Kingdom (England, Scotland, Wales, and Northern Ireland and also the Isle of Man, the Channel Islands, and Gibraltar). It is primarily a demographic or historical research category for people who have at least partial descent from peoples of Great Britain and the modern United Kingdom, i.e. English, Scottish, Welsh, Scotch-Irish, Orcadian, Manx, Cornish Americans and those from the Channel Islands and Gibraltar.

Based on 2020 American Community Survey estimates, 1,934,397 individuals identified as having British ancestry, while a further 25,213,619 identified as having English ancestry, 5,298,861 Scottish ancestry and 1,851,256 Welsh ancestry. The total of these groups, at 34,298,133, was 10.5% of the total population. A further 31,518,129 individuals identified as having Irish ancestry, but this is not differentiated between modern Northern Ireland (part of the United Kingdom) and the Republic of Ireland, which was part of the United Kingdom during the greatest phase of Irish immigration. Figures for Manx and Cornish ancestries are not separately reported, although Manx was reported prior to 1990, numbering 9,220 on the 1980 census, and some estimates put Cornish ancestry as high as 2 million. This figure also does not include people reporting ancestries in countries with majority or plurality British ancestries, such as Canadian, South African, New Zealander (21,575) or Australian (105,152). There has been a significant drop overall, especially from the 1980 census where 49.59 million people reported English ancestry and larger numbers reported Scottish, Welsh and Northern Irish ancestry also.