Besides Missouri, this state was admitted to the Union as a result of the Missouri Compromise of 1820.
Maine
Arizona
Kansas
Ohio
Maine. The 1820 bill allowed Maine to come into the Union as a free state, and Missouri as a slave state, while limiting slavery to south of the parallel 36 degrees 30 minutes. The provisions forbidding slavery north of this line were repealed by the Kansas-Nebraska Act of 1854.