Hillsboro is the 5th most populous city in the U.S. state of Oregon and is the county seat of Washington County. Situated in the Tualatin Valley on the west side of the Portland metropolitan area, the city hosts many high-technology companies, such as Intel, locally known as the Silicon Forest. At the 2020 census, the city's population was 106,447.Settlers founded a community here in 1842, later named after David Hill, an Oregon politician.