Pierce County is a county in the U.S. state of Washington. As of the 2020 census, the population was 921,130, up from 795,225 in 2010, 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.

Geography
According to the United States Census Bureau, the county has a total area of, of which  is land and  (7.6%) is water. The highest natural point in Washington, Mount Rainier, at, is located in Pierce County. Rainier is locally called Tahoma or Takhoma, both native names for the mountain.

Geographic features

 Anderson Island
 Carbon River
 Cascade Range
 Case Inlet
 Commencement Bay
 Fox Island
 Herron Island
 Ketron Island
 Key Peninsula
 Lake Tapps (Washington)
 McNeil Island
 Mount Rainier, highest point in both the county and Washington state.
 Nisqually River
 Puget Sound
 Puyallup River
 Raft Island
 Tacoma Narrows

Pierce County also contains the Clearwater Wilderness area.

Adjacent counties
 King County — north
 Yakima County — east
 Lewis County — south
 Thurston County — west/southwest
 Mason County — west/northwest
 Kitsap County — north/northwest

National protected areas
 Mount Baker-Snoqualmie National Forest (part)
 Mount Rainier National Park (part)
 Nisqually National Wildlife Refuge (part)

Demographics

2020 census
As of the census of 2020, there were 921,130 people, and 335,969 households in the county. The population density was. The racial makeup of the county was 73.1% White, 8.0% African American, 1.8% Native American, 7.4% Asian, 1.8% Pacific Islander, and 7.9% from two or more races. Those of Hispanic or Latino origin made up 12.2% of the population.

23.2% of the population was under 18, and 6.1% of people were under 5. 14.4% of people were over 65. The gender ratio was 49.8% female and 50.2% male. The average household size was 2.65 people.

The median income for a household was $82,574, but the per capita income was $39,036. 8.2% of the population were below the poverty line.

2010 census
As of the census of 2010, there were 795,225 people, 299,918 households, and 202,174 families residing in the county. The population density was. There were 325,375 housing units at an average density of. The racial makeup of the county was 74.2% white, 6.8% black or African American, 6.0% Asian, 1.4% Native American, 1.3% Pacific islander, 3.5% from other races, and 6.8% from two or more races. Those of Hispanic or Latino origin made up 9.2% of the population. In terms of ancestry, 20.5% were German, 13.1% were Irish, 10.7% were English, 6.3% were Norwegian, and 4.2% were American.

Of the 299,918 households, 35.3% had children under the age of 18 living with them, 49.0% were married couples living together, 13.0% had a female householder with no husband present, 32.6% were non-families, and 25.1% of all households were made up of individuals. The average household size was 2.59 and the average family size was 3.09. The median age was 35.9 years.

The median income for a household in the county was $57,869 and the median income for a family was $68,462. Males had a median income of $50,084 versus $38,696 for females. The per capita income for the county was $27,446. About 8.1% of families and 11.6% of the population were below the poverty line, including 15.0% of those under age 18 and 8.2% of those age 65 or over.

History
The area was originally home to the present-day Nisqually, Puyallup, Squaxin, Steilacoom, and Muckleshoot tribes. The majority of Puyallup villages were situated in proximity to the area that would eventually develop into Tacoma, while Nisqually settlements were primarily located in what is now southern Pierce County. The tribes had two main routes: a northern path traversing Naches Pass and a southern route following the Mashel River, which connected them to Eastern Washington tribes. Trade networks among the region's indigenous peoples were well-established long before the arrival of white settlers.

In 1792 British Captain George Vancouver and his party of explorers came via ship to the shores of the region, and named a number of sites in what would become Pierce County, i.e. Mt. Rainier.

In 1832 Fort Nisqually was sited by the British Hudson's Bay Company's chief trader, Archibald McDonald. It was the first permanent European settlement on the Salish Sea. In cooperation with the local indigenous people, a storehouse for blankets, seeds, and potatoes was built at the mouth of Sequalitchew Creek.

In 1839 the Nisqually Methodist Episcopal Mission was established, bringing the first U.S. citizens to settle in the Puget Sound region, near the Sequalitchew Creek canyon.

In 1841 the United States Exploring Expedition set up an observatory on the bluff near the creek to survey, map and chart the waters of Puget Sound.

In 1843 the Second Fort Nisqually was erected. Business became mainly agricultural, and the fort was relocated on a flat-plains area near the banks of Sequalitchew Creek for cattle.
The Fort Nisqually property was turned over to American control in 1859.

In 1846 the Oregon Treaty established the 49th Parallel as the boundary between British Canada and the United States, which left what was to become Pierce County on U.S. territory. In response to increasing tensions between Indians and settlers, the United States Army established Fort Steilacoom in 1849 at the site of the traditional home of the Steilacoom Tribe.

In 1850, Captain Lafayette Balch sited his land claim next to the fort and founded Port Steilacoom. In 1854 the town of Steilacoom became Washington Territory's first incorporated town.

In 1854 the Treaty of Medicine Creek was enacted between the United States and the local tribes occupying the lands of the Salish Sea. The tribes listed on the Treaty of Medicine Creek are Nisqually, Puyallup, Steilacoom, Squawskin (Squaxin Island), S'Homamish, Stehchass, T'Peeksin, Squi-aitl, and Sa-heh-wamish. The treaty was signed on December 26, 1854, by Isaac I. Stevens, governor and superintendent of Indian Affairs of Washington territory at the time. The native tribes were told the treaty would help them by paying them for some of the land. It ended up taking prime farmland and relocating the tribes onto rough reservations. Chief Leschi of the Nisqually tribe protested the treaty. He and his people marched to Olympia to have their voices heard but Isaac Stevens ordered them away. When the natives refused to leave, Isaac Stevens would eventually call martial law and - after the beginning of the Puget Sound War in 1855 - initiate a search for Chief Leschi in order to arrest him. Chief Leschi was eventually captured and put on trial. The first jury couldn't come to a verdict, so Isaac Stevens had the trial done a second time. This time Leschi was found guilty. Chief Leschi was hanged on February 19, 1858. On December 10, 2004, a historical court convened in Pierce County ruled "as a legal combatant of the Indian War Leschi should not have been held accountable under law for the death of an enemy soldier," thereby exonerating him of any wrongdoing.

Government

Pierce County has adopted and is governed by a Charter. This is allowed by section 4 of Article XI of the Washington State Constitution. The Pierce County Executive, currently Bruce Dammeier (R), heads the county's executive branch. The Assessor-Treasurer Mike Lonergan, auditor Julie Anderson, Prosecuting Attorney Mary Robnett, and Sheriff Ed