Provisional and Territorial Records Guide
Jefferson County History and Records
Jefferson County was created by the territorial legislative assembly on December 22, 1852 and was named for Thomas Jefferson, who had shown much interest in the settlement of the northwest. Port Townsend was selected as the county seat.
Jefferson County was located on the Olympic Peninsula and was bordered on the north by latitude 49'; on the east by Island County; on the south by a line from Pilot Cove to the Pacific Ocean; and on the west by the Pacific Ocean.
The creation of Clallam County in 1854 left Jefferson County with shorelines on both Puget Sound and the Pacific Ocean and an impenetrable mountain barrier, the Olympics, occupying the central part of the county. This effectively divided the county into two distinct portions. Contact between the two areas had to be maintained through Clallam County.
The same act that created Jefferson County also established two election precincts, one at Port Townsend, the other at New Dungeness. It was not until two weeks later that a bill passed which set the county seat at Port Townsend on the land claim of Alfred Plummer. On January 10, 1853, an act appointing county officers created a county government consisting of three commissioners, a sheriff, and a probate clerk. On March 2, 1853, Washington Territory was created, removing Jefferson County from the jurisdiction of Oregon Territory.