Which state was added to the United States shortly before the current flag design was introduced?

The state that was added to the United States shortly before the current flag design was introduced is Hawaii. Hawaii became the 50th state on August 21, 1959. The design of the current U.S. flag, featuring 50 stars, was adopted on July 4, 1960, following Hawaii's admission to the Union. This flag showcases a star for each state, and since Hawaii was the last state to be added at that time, its admission directly influenced the design and composition of the flag.

The timing of Hawaii's statehood is critical, as the other states listed were admitted earlier. Alaska, for example, became the 49th state on January 3, 1959, and while it preceded Hawaii's admission, the flag was not updated to incorporate Alaska's star until the addition of Hawaii brought the total to 50 stars. Thus, recognizing Hawaii's significance in the context of the current flag design confirms its status as the correct answer.