Shelton is a city located in the state of Washington within the United States. It serves as the county seat for Mason County and holds the distinction of being the westernmost city on Puget Sound. The municipality sits at coordinates 47.2217 north latitude and 123.1256 west longitude, positioning it prominently along the waterway that defines much of the region's geography and economic history.

The area was originally inhabited by the Squaxin Island Tribe, known as the People of the Waters, who managed the land for centuries before contact with settlers. Following the Treaty of Medicine Creek in 1854, David Shelton and his wife Frances claimed 640 acres under the Donation Land Claim Act. The settlement was officially incorporated in 1890 and named after David Shelton, a delegate to the territorial legislature.

The city's landscape was historically dominated by the Simpson Timber Company mill on Oakland Bay, which was sold to Sierra Pacific Industries in 2015 for new construction. Shelton once featured a fleet of steamboats known as the Puget Sound Mosquito Fleet, including vessels like the Old Settler and City of Shelton. The Ridge Motorsports Park, opened in 2012, hosts MotoAmerica and Trans-Am Series races, adding a modern recreational landmark to the area.

Shelton identified itself as Christmastown, USA, due to the local cultivation of Christmas trees, a name later revived for an annual festival. The community maintains a rich cultural heritage through notable figures such as Olympic medalists Karol Kennedy and Desmond Koch, as well as former NFL players Raul Allegre and Justin Ena. These individuals highlight the city's contributions to sports and entertainment beyond its industrial roots.

As of the 2020 census, Shelton had a population of 10,371 residents living in a total area of 6.09 square miles. The economy was built around logging, farming, dairying, ranching, and oyster cultivation. The city experiences a warm summer Mediterranean climate with cold winters, characterized by extremely precipitous rainfall in winter and dry summers with less than 33 mm of precipitation in the driest month.