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. Grays Harbor County is included in the Aberdeen Micropolitan Statistical Area.
The county is presently named after a large estuarine bay near its southwestern corner. On May 7, 1792, Boston fur trader Robert Gray crossed the bar into a bay which he called Bullfinch Harbor, but which later cartographers would label Chehalis Bay, and then Grays Harbor.
source: wikipedia.org