Pierce County, Washington

Pierce County, Washington
Location within the U.S. state of Washington
Coordinates: 47°03′05″N 122°09′12″W / 47.051413°N 122.15324°W / 47.051413; -122.15324
Country United States
State Washington
FoundedDecember 22, 1852 (created)
Named afterFranklin Pierce
SeatTacoma
Largest cityTacoma
Government
 • County ExecutiveRyan Mello
Area
 • Total
1,805.491 sq mi (4,676.20 km2)
 • Land1,668.025 sq mi (4,320.16 km2)
 • Water137.466 sq mi (356.04 km2)  7.61%
Population
 (2020)
 • Total
921,130
 • Estimate 
(2024)
941,170
 • Density552.23/sq mi (213.22/km2)
Time zoneUTC−8 (Pacific)
 • Summer (DST)UTC−7 (PDT)
Area code253, 360, 564
Congressional districts6th, 8th, 10th
Websitepiercecountywa.gov

Pierce County is a county in the U.S. state of Washington. As of the 2020 census, the population was 921,130, and was estimated to be 941,170 in 2024, making it the second-most populous county in Washington, behind King County, and the 60th-most populous in the United States. The county seat and largest city is Tacoma, Formed out of Thurston County on December 22, 1852, by the legislature of Oregon Territory, it was named for U.S. President Franklin Pierce. Pierce County is in the Seattle metropolitan area (formally the Seattle-Tacoma-Bellevue, WA, metropolitan statistical area).

Pierce County is home to the volcano Mount Rainier, the tallest mountain in the Cascade Range. Its most recent recorded eruption was between 1820 and 1854. There is no imminent risk of eruption, but geologists expect that the volcano will erupt again. If this should happen, parts of Pierce County and the Puyallup Valley would be at risk from lahars, lava, or pyroclastic flows. The Mount Rainier Volcano Lahar Warning System was established in 1998 to assist in the evacuation of the Puyallup River valley in case of eruption.