How many states joined the USA during the 20th century?

The United States of America is a federal republic consisting of 50 states, a federal district (Washington, D.C., the capital city of the United States), five major territories, and various minor islands.

There were five states that joined the USA during the 20th century. Oklahoma became the 46th state to enter the union on November 16, 1907. New Mexico was admitted to the Union as the 47th state on January 6, 1912. Arizona is the 48th state and last of the contiguous states to be admitted to the Union, achieving statehood on February 14, 1912. Alaska was admitted as the 49th state of the U.S. on January 3, 1959. Hawaii is the most recent state to join the union, on August 21, 1959.

The largest state by population is California, with a population of 39,538,223 people, while the smallest is Wyoming, with a population of 576,851 people; the federal district has a larger population (689,545) than both Wyoming and Vermont. The largest state by area is Alaska, encompassing 665,384 square miles (1,723,337 square kilometers), while the smallest is Rhode Island, encompassing 1,545 square miles (4,001 square kilometers).