Missouri Emigration and Immigration
A few thousand French settlers remained in the area after the United States bought Missouri as part of the Louisiana Purchase in 1803, but most pre-statehood settlers were Americans of English and Ulster Scots origin. They came mainly from the Kentucky, Tennessee, Virginia, Ohio, Indiana, and Illinois. Settlement spread up the river valleys into central Missouri by the 1820s and into western Missouri by the 1830s. Mormon immigrants settled western Missouri in 1831 but were driven from the state in 1839.
Both the Santa Fe Trail and the Oregon Trail began at Independence, Missouri. Many Missourians followed these trails westward to California, Texas, Oregon, Colorado, Oklahoma, and Kansas. In spite of this emigration from the state, Missouri was the fifth most populous state in the United States at the close of the Civil War.
Overseas immigration to Missouri began in earnest in the 1830s when large numbers of Germans began to settle the farm country west of St. Louis and south of the Missouri River known as the "Missouri Rhineland." Beginning in the 1840s German and Irish immigrants settled in urban centers. After 1880, St. Louis and Kansas City attracted groups of Italians, Greeks, Poles, and east European Jews.
An especially helpful description of settlement patterns in Missouri is in Milton D. Rafferty, Historical Atlas of Missouri (Norman, Oklahoma: University of Oklahoma Press, 1982; FHL book 977.8 E7r).
Before the Civil War the Ohio-Mississippi-Missouri river system was the major migration route to Missouri. New Orleans was the favorite port of entry for early German immigrants to Missouri. After the war, most settlers came by railroad through the lower midwestern states. To find an immigrant ancestor, you may want to check ship passenger lists for East Coast ports and for the Port of New Orleans. More detailed information on immigration sources is in the United States Research Outline.