Hillsboro is the fifth-largest city in the State of Oregon and is the county seat of Washington County. Lying in the Tualatin Valleyon the west side of the Portland metropolitan area, the city hosts many high-technology companies, such as Intel, that comprise what has become known as the Silicon Forest.
The first people of the Tualatin Valley were the Atfalati or Tualaty tribe of the Kalapuya, who inhabited the region for up to 10,000 years before white settlers arrived. The valley consisted of open grassland maintained through annual burning by the Atfalati, with scattered groves of trees along the streams. The Kalapuya moved from place to place in good weather to fish and hunt and to gather nuts, seeds, roots, and berries. Important foods included camas and wapato, and the Atfalati traded for salmon from Chinookan tribes near Willamette Falls on the Willamette River. During the winter, they lived in longhouses in settled villages, some near what became Hillsboro and Beaverton. Their population was greatly reduced after contact in the late 18th century with Europeans, who carried smallpox, syphilis, and malaria. Of the original population of 1,000 to 2,000 Atfalati reported in 1780, only 65 remained in 1851. In 1855, the U.S. government sent the survivors to the Grande Ronde reservation further west.