Franklin County, MO
History
Occupied by succeeding cultures of indigenous peoples, this area was populated by the historic Osage tribe at the time of European encounter. The region was first settled by Europeans during the rule of the Spanish Empire. The Spanish log fort San Juan del Misuri (1796–1803) was built in present-day Washington. After the American Revolutionary War, migrants from the new United States started moving West. Among them were the family and followers of Daniel Boone, an explorer who settled the area starting in 1799.Source Wikipedia
Franklin County was established in 1818, two years before Missouri was admitted to the Union as a state. When the Missouri Territory was organized in 1812, there were only five counties: St. Charles, St. Louis, St. Genevieve, Cape Girardeau and New Madrid. Franklin County was once part of St. Louis County. Between 1812 and 1820, the number of counties increased to 15 with the addition of Washington (1813), Howard (1816), and Jefferson, Franklin, Wayne, Lincoln, Madison, Montgomery, Pike and Cooper (all 1818).
Source Franklin County History