The following important events in the history of Missouri affected political boundaries, record keeping, and family movements.
- 1735 French lead miners established the first permanent white settlement at Sainte Genevieve.
- 1763 France ceded the Missouri area to Spain. French fur traders founded St. Louis in 1764.
- 1800 Spain returned the region to France.
- 1803 France sold Missouri to the United States as part of the Louisiana Purchase. Missouri was part of the Louisiana Territory after 1805.
- 1812 Congress created the Missouri Territory. Many families left after earthquakes and other disasters.
- 1821 Missouri became a state.
- 1837 The Platte Purchase added six northwestern counties to the state.
- 1861-1865 During the Civil War most of the citizens supported the Union, although several counties seceded. Troops from Missouri served in both the Confederate and the Union forces.
Major research centers have histories of the state and its counties. An especially helpful source for studying the history of Missouri before statehood is Louis Houck,A History of Missouri from the Earliest Explorations and Settlements until the Admission of the State into the Union, Three Volumes. (Chicago, Illinois: R. R. Donnelley, 1908; FHL book 977.8 H2h; vols. 1-2 on film 1697679 items 2-3; vol. 3 on film 1320710).
For a list of published county histories, see Paul O. Selby,A Bibliography of Missouri County Histories and Atlases, 2d ed. (Kirksville, Missouri: Northeast Missouri State Teachers College, 1966; FHL book 977.8 A1 No. 145).