Which U.S. state was the last to join the Union?

Hawaii was the last U.S. state to join the Union, being admitted on August 21, 1959. This marked an important moment in American history as it expanded the nation into the Pacific region and contributed to the cultural diversity of the United States. The admission of Hawaii also reflected a growing recognition of the islands' strategic and economic significance following World War II.

Understanding the context of Hawaii's admission involves recognizing its unique history, including its prior status as a U.S. territory and the political shifts that led to its statehood. It stands apart from the other states listed, as they joined the Union much earlier. Alaska became a state in 1959, while Arizona joined in 1912 and Oklahoma in 1907, illustrating Hawaii's position as the most recent addition to the United States.