This is the Washington State Tartan!
The fabric was designed by Margaret McLeod van Nus and Frank Cannonito in 1991, with a background of green to represent the rich forests of “The Evergreen State.” The bands of color have the following significance:
blue for the lakes, rivers and ocean;
white for the snow-capped mountains;
red for the apple and cherry crops;
yellow for the wheat and grain crops;
black for the eruption of Mount St. Helens