Hawaii was the last state to join the United States, becoming a state on Aug. 21, 1959. Hawaii is the only state in the nation made up entirely of islands, and it is one of the smallest states.
The Hawaiian islands are the top portions of volcanoes, some of which remain active today. Captain James Cook, a British explorer, named the islands the "Sandwich Islands" in 1778 after his sponsor, the Earl of Sandwich. The United States had a naval base in Hawaii at Pearl Harbor long before Hawaii became a state. This base was attacked on Dec. 7, 1941, by Japan, bringing the United States into World War II.