In 1846, the district of Tuality in the Oregon Territory became Tuality County. In 1849, the name was changed to Washington County. Boundary lines were drawn and redrawn until finally in 1855 the shape of Washington County became close to what it is today. In 1853, the first county government was constituted with five members: three Judges, a Sheriff and a Treasurer.
The first courthouse in the county was a simple log cabin situated on a 40-acre plot of land near what is now NW 253rd Avenue.
In its 150 years of service to Washington County, the courthouse has changed its location and face several times, but still serves as the symbol of justice for the citizens of Washington County.