Louisiana

Louisiana west of the Mississippi River was mostly part of the Louisiana Territory, which was ceded by Spain to France in 1803 and then sold by France to the United States. In 1804 much of the present State was included in the newly established Orleans Territory; the rest of the Louisiana Purchase became Louisiana Territory, renamed Missouri Territory in 1812. Louisiana was admitted as a State on April 30, 1812 and immediately added the Florida Parishes east of the Mississippi and north of Lake Pontchartrain, although these still were claimed by Spain until 1819. Also in 1819, the boundary with Mexico (Texas) was settled by treaty, bringing the State to essentially its present limits.

In 1810 the census covered most of the settled parts of what is now Louisiana, except for the Florida Parishes east of the Mississippi River. By 1820 census coverage extended to virtually all of the present State. Louisiana's primary subdivisions have long been termed parishes instead of counties; both terms appear in early censuses.