The 49th and 50th states to join the United States were Alaska and Hawaii, respectively. Alaska joined on Jan. 3, 1959, while Hawaii joined on August 21 of the same year.
Prior to Alaska's statehood, no state had joined the United States since Arizona, which became a state in 1912. As of 2014, Alaska and Hawaii are the last two states to have joined the United States; however, Puerto Rico voted to begin seeking statehood in 2012, and some residents of Washington D.C. have clamored for statehood as well. Both areas want statehood because they lack direct representation in the national government. States such as California have discussed splitting themselves into smaller states to increase the responsiveness of their state and federal governing officials.