The cession of the Floridas stands out as one of the greatest victories in the history of American diplomacy. Ownership of Florida insured to the United States a continuous seaboard on the Atlantic Ocean. It led to the recognition by the United States of the South American colonies, then in revolt against Spain. The treaty with Spain gave the United States its first recognized claim to the western lands bordering on the Pacific Ocean. 2 It became the basis for the acquisition of Oregon and Washington, and parts of present day Montana and Idaho. Cession led directly to the Monroe Doctrine.
"The Cession of Florida and John Quincy Adams, Secretary of State,"
Florida Historical Quarterly: Vol. 36:
3, Article 4.
Available at: https://stars.library.ucf.edu/fhq/vol36/iss3/4