Described as one of the 'best buys' of the millennium which (State) was purchased in 1819 from Spain for 5 Million Dollars by the US?

Florida was purchased from Spain in 1819 through the Adams-Onís Treaty for $5 million. This acquisition is often described as one of America's best land purchases, given the territory's strategic location and agricultural potential. Kansas was acquired through different means, Madrid is in Spain, and Alaska was purchased from Russia in 1867.