You will be given a trivia clue, and the category it belongs to. You should answer with the best answer that belongs in the category and is described by the clue. For simplicity, answers should be in all lower cased letters.

Category: "W"HODUNNIT? 
Clue: He was the first U.S. president to be unanimously elected
george washington

Category: THE 19th CENTURY 
Clue: 1853 purchase that brought the contiguous U.S. about up to its present area
the gadsden purchase

Category: DOWN EASTERS 
Clue: This woman born in Hampden helped open hospitals for the mentally ill in over 15 states

dorothea dix