Cosmopolis is a small city in Grays Harbor County, Washington, on the Chehalis River and U.S. Route 101 immediately southeast of Aberdeen. Despite its modest size, it holds a notable distinction: it is the oldest city on Grays Harbor, tracing its roots to a donation land claim filed in 1852 and its incorporation in 1891. The name, recorded in 1853, means "city of the world," though locals far more often use the affectionate nickname "Cosi." The community's economy long centered on the Chehalis River, first as a mill town and, from the mid-twentieth century onward, around a large pulp mill that produced specialty pulps for products ranging from photographic papers to acetate yarns. That industrial chapter is a defining part of Cosmopolis' identity and its landscape, and its legacy continues to shape the city's character even as the broader Grays Harbor economy has shifted. Cosmopolis developed residential areas on its wooded hillsides through the latter half of the twentieth century and into the 2000s, giving the city a greener, quieter feel than its larger neighbor. It has tended to attract a somewhat higher-income population than other parts of Grays Harbor County, along with a strong sense of community pride. With about 1,600 residents, Cosmopolis offers a small, neighborly setting immediately adjacent to Aberdeen's jobs, schools, and services. Makarenko Park, a 39-acre preserve with more than two miles of trails, anchors local recreation. For people who want the practical advantages of the Aberdeen–Hoquiam area with more space and a slower pace, Cosmopolis is an appealing choice.