Illustrations / Flags and Seals / Washington Flags and Seals / Washington Shape Flag
About the Official flag of the state of Washington
Washington’s flag is the only state flag on a field of green; an appropriate color for the evergreen state (Washington’s unofficial nickname).
Washington also has the only state flag displaying an image of an actual person (George Washington, first president of the United States of America).
Source: https://statesymbolsusa.org