Hawaii became the 50th U.S. state, joining the union on August 21, 1959. Its admission completed the current sequence of states and established the statehood milestone associated with the modern American flag.
Hawaii's statehood followed Alaska's admission as the 49th state earlier in 1959. President Dwight D. Eisenhower signed the Hawaii Admission Act, and Hawaii voters approved statehood in a referendum. The new state consisted of islands in the central Pacific, making it geographically distinct from the contiguous United States.
The change also affected the national flag. A 50-star flag was designed for Hawaii's admission and first officially flown on July 4, 1960. The flag's stars represent the states, so Hawaii's admission explains why the current design has 50 stars. Puerto Rico, the District of Columbia, and other U.S. territories are not states and therefore are not represented by additional stars.