The Last of the Floatplanes
While it's dangerous to cite an aircraft as being the "first" or "last," one is safe in describing the Curtiss SC Seahawk as the U.S. Navy's last operational floatplane. Significantly, the Seahawk is also believed to be the only American aircraft design initiated after the United States entered World War II that saw action in that conflict.
In the years immediately after World War I, the U.S. Navy developed a series of seaplanes for operation from battleships and cruisers, primarily to provide observation for the ships' big guns. Subsequently, these aircraft also took on the role of scouting (usually done in the between-wars period by large flying boats and, in limited numbers, airships). And, in World War II, in addition to gunnery observation/spotting and scouting, these aircraft rescued pilots downed at sea.1