The state flag has undergone minor revisions since its adoption, including the use of standardized colors in 1955 and a modernized seal in 1967.

[2][3] Another popular design was a purple or green flag bearing the state seal in gold.

[5] Governor Ernest Lister became a supporter of the idea, issuing a call for designs from the state's citizens and city organizations.

[9] The Washington chapter of the Daughters of the American Revolution (DAR) began a campaign to adopt an official state flag during the Alaska–Yukon–Pacific Exposition of 1909, a world's fair hosted in Seattle.

[10] In 1914, the national DAR requested that the Washington chapter send a state flag to be displayed in the DAR Memorial Continental Hall in Washington, D.C.[11] Upon discovering that the state lacked a suitable flag, the DAR formed a design committee, led by Emma Chadwick (wife of Washington Supreme Court justice Stephen J. Chadwick), to design a state flag.

The DAR's flag, adopted in 1915, consisted of a green background with the state seal in the center.

The flag would fly aboard the USS Vicksburg, representing the state nautical school during a voyage along the West Coast and to Hawaii.

[11][16] The DAR renewed its lobbying for a state flag in 1922, having gained the approval of the Sons of the American Revolution and other civic organizations.

[3] A bill adopting the state flag was introduced in the 1923 legislative session and passed unanimously in the Senate by February,[17] and the House of Representatives on March 5, 1923.

[18] The governor's approval was not required and the bill became law, formally adopting the state flag.

[2][36] According to Senator Guy B. Groff, sponsor of the 1923 bill that adopted the flag, the flag's green field represented the "verdant fields" of Western Washington, while the gold seal represented the "wheat areas" of Eastern Washington.