Query: Pierce County, Washington is the location of the highest mountain of the Cascade Range of the Pacific Northwest.

Relevant passages:
Cascade Range <=SEP=> The Cascade Range or Cascades is a major mountain range of western North America , extending from southern British Columbia through Washington and Oregon to Northern California . It includes both non-volcanic mountains , such as the North Cascades , and the notable volcanoes known as the High Cascades . The small part of the range in British Columbia is referred to as the Canadian Cascades or , locally , as the Cascade Mountains . The latter term is also sometimes used by Washington residents to refer to the Washington section of the Cascades in addition to North Cascades , the more usual U.S. term , as in North Cascades National Park . The highest peak in the range is Mount Rainier in Washington at 14411 ft.   part of the Pacific Ocean 's Ring of Fire , the ring of volcanoes and associated mountains around the Pacific Ocean . All of the eruptions in the contiguous United States over the last 200 years have been from Cascade volcanoes . The two most recent were Lassen Peak from 1914 to 1921 and a major eruption of Mount St. Helens in 1980 . Minor eruptions of Mount St. Helens have also occurred since , most recently from 2004 -- 2008 . The Cascade Range is a part of the American Cordillera , a nearly continuous chain of mountain ranges ( cordillera ) that form the western `` backbone '' of North America , Central America , and South America .

Mount Rainier <=SEP=> Mount Rainier ( pronounced : -LSB- reɪˈnɪər -RSB- ) , Mount Tacoma , or Mount Tahoma is the highest mountain of the Cascade Range of the Pacific Northwest , and the highest mountain in the U.S. state of Washington . It is a large active stratovolcano located 54 mi south-southeast of Seattle , in the Mount Rainier National Park . It is the most topographically prominent mountain in the contiguous United States and the Cascade Volcanic Arc , with a summit elevation of 14411 ft.   Mt. Rainier is considered one of the most dangerous volcanoes in the world , and it is on the Decade Volcano list . Because of its large amount of glacial ice , Mt. Rainier could produce massive lahars that could threaten the entire Puyallup River valley , and poses a grave threat to the southern sections of the Seattle metropolitan area , a city of over 650,000 people with more than 3.7 million living in its metropolitan area .

Pierce County, Washington <=SEP=> right | thumb | Tacoma -- seat of Pierce County   Pierce County is a county in the U.S. state of Washington . As of the 2010 Census , the population was 795,225 , making it the second-most populous county in Washington behind King County . 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 notable for being home to Mount Rainier , the tallest mountain and a volcano 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 .