After American Independence, Spain's hold on Florida was tenuous, and numerous boundary disputes arose. After years of negotiation in 1819, John Quincy Adams (who at the time was, Secretary of States) signed Florida Purchase Treaty.The only costs were the assumptions of $5 million of claims by U.S. citizens against Spain. Florida was organized as a U.S. territory in 1822 and was admitted into the Union as a slave state in 1845.