Grays Harbor County is a
county in the
U.S. state of
Washington. As of the
2010 census, the population was 72,797. The
county seat is
Montesano, and its largest city is
Aberdeen. The county is named after a large estuarine bay near its southwestern corner. On May 7, 1792, Boston fur trader Robert Gray crossed the bar into the bay he called Bullfinch Harbor, but which later cartographers would label Chehalis Bay, and then Grays Harbor.