I think they named the dam after him because he was president of the US at the time and got the congress to go along with funding it. Franklin Roosevelt tried to rename it Boulder Dam, but nobody was buyin' it.
Yup, JFK really had a flair for delivering speeches and really great speech writers to back him up.
Amusement: Most of JFK's speeches don't get quoted these days. It just would not be politically correct to see St. John pounding the pulpit and yelling, "There are too many communists in the State Department!"