Sumner is a city in northern Pierce County, Washington, United States. The population was 9,451 at the 2010 census. Nearby cities include Puyallup to the west, Auburn to the north, and Bonney Lake to the east.
Sumner was founded in 1853 as Stuck Junction and platted in 1883 by George H. Ryan, in anticipation of a stop on the Northern Pacific Railway. The town was named "Franklin" until 1891, when the Post Office Department requested that the name be changed to avoid confusion with similarly named towns. The name of abolitionist Senator Charles Sumner was chosen for the town after a lottery.
Sumner is located at 47°12′21″N 122°14′9″W (47.205823, -122.235803).
According to the United States Census Bureau, the city has a total area of 7.62 square miles (19.74 km2), of which, 7.51 square miles (19.45 km2) is land and 0.11 square miles (0.28 km2) is water.
After Orting, Sumner and Puyallup are geographically next in line to be hit by lahars whenever Mount Rainier erupts in the future. This is depicted in the Modern Marvels episode titled "Most Dangerous," which shows a simulation of a lahar flooding the Orting and Puyallup Valleys from an eruption.
As of the 2010 census, there were 9,451 people, 3,980 households, and 2,454 families living in the city. The population density was 1,258.5 inhabitants per square mile (485.9/km2). There were 4,279 housing units at an average density of 569.8 per square mile (220.0/km2). The racial makeup of the city was 87.3% White, 1.2% African American, 1.0% Native American, 2.4% Asian, 0.4% Pacific Islander, 3.4% from other races, and 4.3% from two or more races.