King and Pierce are the most populated counties, and they have the greatest number of people in prisons.
Grays Harbor has the highest imprisonment rate in the state. That’s according to a recent report based on census data when looking at county by county trends. King and Pierce are the most populated counties, and they have the greatest number of people in prisons. But, according to the Prison Policy Initiative, Grays Harbor County had 470 per 100,000 people in prison. Other counties in western Washington with high imprisonment rates include Cowlitz County with 417 per 100,000 and Lewis County with 364 per 100,000.