On February 17, the Senate voted to bar slavery outside Missouri in the part of the Louisiana Purchase north of the 36°30′ north latitude line, with Johnson voting in favor. The bill passed, and was signed by President Monroe in March. Missouri's admission was delayed due to controversial clauses in its draft constitution, such as one forbidding the entry to the state of free African-Americans. Johnson served on the committee of House and Senate members which brokered a resolution, enabling Missouri's admission in August 1821.