Washington County is one of the 36 counties in the U.S. state of Oregon. As of the 2010 United States Census, the population was 529,710, making it the state's second most populous county and most populous "Washington County" in the United States. The county seat and largest city is Hillsboro.

Where is Washington County in the state of Minnesota?

As one of Minnesota's original nine counties, Washington County is on the eastern edge of the Twin Cities Metropolitan area, composed of 423 square miles of land, and possessing a distinct set of landscapes and resources. It runs more than 40 miles in length, and encompasses 468 lakes of 10 acres or more in area.

How many states have a Washington County?

Washington County is the most common county name in the U.S. Thirty-one states have one – or a Washington Parish, in the case of Louisiana – but their shared moniker can mask divergent histories, economies and environments that make each Washington County a unique place to live.