What treaty established U.S claims to Florida and gave the U.S access to the Pacific.?

The Adams-Onís Treaty, signed in 1819, established U.S. claims to Florida and defined the boundaries between the U.S. and New Spain. In this treaty, Spain ceded Florida to the United States in exchange for the U.S. assuming $5 million in claims by American citizens against Spain. Additionally, it clarified U.S. access to the Pacific by setting the western boundary of the Louisiana Purchase, helping to secure American expansion westward.