Question

The political balance between slave and free states as of 1819 was disturbed by

Answer 1

the political balance between slave and free states was disturbed by the petition of Missouri for admission to the union as a slave state.

Answer 2

The political balance between slave and free states as of 1819 was disturbed by the petition of the territory of Missouri for admission to the Union as a slave state.

As a result of the Missouri compromise Maine was admitted in the United States as a free state and Missouri was a slave state then. This compromise was passed in 1820. The goal of the Missouri Compromise was to keep the balance of power between slave and free states in Congress.