Pacific is a city in King and Pierce counties in the State of Washington. Located primarily in King County, the population was 7,235 at the 20…Pacific is a city in King and Pierce counties in the State of Washington. Located primarily in King County, the population was 7,235 at the 2020 census. Pacific was platted on April 10, 1906, by real estate promoter Clarence Dayton Hillman as "C.D. Hillman's Pacific City Addition to the City of Seattle". The development would take advantage of the nearby Puget Sound Electric Railway, which provided connections to Seattle and Tacoma. It was officially incorporated as a town on August 10, 1909.