Eighteenth largest state by area, Washington is the northwestern-most state in the contiguous United States. There are 39 counties in “The Evergreen State.” The first two counties (Clark County and Lewis County) were created from an unorganized territory in 1845. These counties were named after the Lewis and Clark Expedition. Carved out of Stevens County in 1911, Pend Oreille County is the most recently formed.
King County is the most populous and the 13th most populous county in the US. Seattle, the the seat of King County, is the largest city in the Pacific Northwest region. Garfield County is both the least populous and the least densely populated county in Washington. Okanogan County, at 5,268 square miles, is the largest county by area in the state. San Juan County, the smallest by area, is the only county in Washington not served by state highways, due to its location in the Salish Sea. Mount Rainier, the tallest mountain in the Cascade Range, is located in Pierce County.
Counties in Eastern Washington:
Counties in Western Washington:
List of Counties in Washington