No, Puerto Rico is a commonwealth of the United States. In 1898, the United States acquired the island of Puerto Rico from Spain, but Puerto Rico did not become a commonwealth until 1952. Though Puerto Ricans pay no federal income tax and cannot vote for President, they are citizens of the United States and can move freely around the country. Puerto Rico is allowed one representative to the House of Representatives, but that member cannot vote. With approximately 3.6 million residents, Puerto Rico is currently the largest colony in the world.
A view of Old San Juan in Puerto Rico, which is still a commonwealth of the United States and not a state.