There are 50 states in the United States as of 2015. Washington, D.C., the national capital, is not considered a state, but is a federal district. Besides the federal district, the United States also has dependencies and territories.
The United States' territories include Puerto Rico, American Samoa, the U.S. Virgin Islands, the Northern Mariana Islands and Guam.
Forty-eight of America's 50 states are contiguous. The only states that are not are the newest states. Hawaii, which became the last state to join the union on August 21, 1959, is in Polynesia, and Alaska, which joined the union on January 3, 1959, is separated from the lower 48 states by western Canada.