State Route 16 (SR 16) is a 27.16-mile-long (43.71 km) state highway in the U.S. state of Washington, connecting Pierce and Kitsap counties. The highway, signed as east–west, begins at an interchange with Interstate 5 (I-5) in Tacoma and travels through the city as a freeway towards the Tacoma Narrows. SR 16 crosses the narrows onto the Kitsap Peninsula on the partially tolled Tacoma Narrows Bridge and continues through Gig Harbor and Port Orchard before the freeway ends in Gorst. The designation ends at an intersection with SR 3 southwest of the beginning of its freeway through Bremerton and Poulsbo. SR 16 is designated as a Strategic Highway Network (STRAHNET) corridor within the National Highway System as the main thoroughfare connecting Tacoma to Naval Base Kitsap and a part of the Highways of Statewide Significance program.

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 59th-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.