Ohio

The Ohio Burgee is the official flag of the U.S. state of Ohio. It is a triangular swallowtail flag. Its red, white, and blue elements symbolize the state's natural features and order of admission into the Union. A prominent disc in the flag's triangular canton is suggestive of the state's name. The flag was adopted in 1902. In addition to resembling the letter O and a buckeye nut, the flag's annulus also represents "the original territory of Ohio" in the Northwest Territory. Ohio's flag is the only non-rectangular U.S. state flag.

Text modified from "Flag of Ohio" on Wikipedia which is licensed under CC BY-SA 4.0.