The State of Hawaii flag hangs at our house to commemorate Hawaii Statehood Day. President Dwight D. Eisenhower signed a proclamation making Hawaii the 50th state on Friday, August 21, 1959. Rather than commemorate it on the 21st, Hawaiians celebrate Statehood on the third Friday of August. They usually get the day off, which is pretty cool because the rest of us don't normally have a good excuse to take off in August.
This flag can also work for King Kamehameha Day June 11, but that's pretty close to Flag Day in the rest of the United States (June 14).