Question

What was the treaty in which the U.S. purchased Florida?

Answer 1

Florida Purchase Treaty

Answer 2

The Adams-Onis Treaty of 1819 also know as the Transcontinental Treaty or the purchase of Florida. This was a treaty between the United States and Spain in 1819 that gave Florida to the U.S. and set out a boundary between the U.S. and New Spain (now Mexico).
http://en.wikipedia.org/wiki/Adams%E2%80%93On%C3%ADs_Treaty