Washington County (Or.)

The Provisional Legislature created Washington County as Tuality District on July 5, 1843, as one of the four original counties created in Oregon. Tuality County was bordered on the north by latitude 54@ 40 , on the east by Clackamas County, on the west by the Pacific Ocean, and on the south by Yamhill County. In 1844, the Columbia River was made the northern boundary of Tuality County and Clatsop County was created from Tuality County's western half. In 1849, the Territorial Legislature changed the name of Tuality County to Washington in honor of President George Washington. Washington County obtained its present boundaries in 1854 with the creation of Columbia County to the north and Multnomah County to the east. The area of Washington County is 727 square miles.

Columbia was selected as the county seat in 1850. Later, the town was given the name of Hillsborough, which in 1858 was modified to Hillsboro. After meeting in two local church buildings, a permanent county headquarters was built in 1852. A brick courthouse was built in 1873 and remodeled in 1891. In 1912 an annex was built. A new courthouse was built in 1927 to replace the original brick structure. The Justice Services Building was added on to the courthouse in 1972. The Public Services Building was constructed in 1990 to house offices of the clerk, assessor, surveyor, planner, and human services.

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