As early as 1817, Missourians seeking to move beyond territorial status began petitioning Congress for statehood. At the time, the 22 states comprising the United States of America were divided equally between slave states and free states, balancing representation in Congress. Because admitting Missouri as a state would tip the balance one way or the other, debate ensued over what to do with Missouri's application.

While the debate over Missouri was pending, the citizens of the Maine Territory also applied for statehood. With both applications before Congress, Senator Henry Clay of Kentucky proposed a compromise – in exchange for Missouri's admission as a slave state, the northern territory of Maine would be admitted as a free state, ensuring representation in Congress remained equal.

The Missouri Compromise, as it came to be known, also banned slavery north of a particular latitude line running through the Louisiana Purchase. Although most of Missouri's territory is north of that line, it was exempted from the slavery ban. 

Congress approved the compromise and granted Maine statehood in March 1820. Due to further concerns with a provision in Missouri's constitution, however, a "second Missouri compromise" was necessary. The Missouri territorial legislature approved this compromise in June 1821, and Congress granted Missouri statehood. President James Monroe signed the federal legislation August 10, 1821, officially making Missouri the 24th state in the union.

Nonetheless, Missouri's official state seal – adopted by the state legislature in January 1822 – reflects the date of 1820. This is the year when Missouri's first constitution was adopted and the year Missouri began functioning as though it were a state, even though it officially was not recognized as such until the following year.

(More information about the bicentennial of Missouri's statehood and relevant state history is available from the official Missouri 2021 bicentennial website.)

Top image: Citizens of Missouri Territory, Missouri Statehood Petition, 1817, The Missouri Collection (Collection # C3982). Image courtesy of The State Historical Society of Missouri, Columbia, Missouri.

Bottom image: Missouri state flag. Image courtesy of the Missouri State Archives, Office of the Secretary of State, Jefferson City, Missouri.