Cosmopolis is a city in Grays Harbor County, Washington, United States.

[6] This region experiences warm (but not hot) and dry summers, with no average monthly temperatures above 71.6 °F.

Cosmopolis is home to Mill Creek Park, a 39-acre (16 ha) green space that contains a pond.

[9] Also listed as 39 acres (16 ha) is Marenko Park, located on the city's west side.

[10] In 2006, the Weyerhaeuser pulp mill in Cosmopolis shut down, costing the local community 245 jobs.

Previously, in late 2005, the Weyerhaeuser large-log saw mill in Aberdeen closed, losing 95 jobs.

As part of the Chehalis Basin Strategy, a concrete, steel, and earthen dam was constructed on Mill Creek.

Completed in 2018, the $3.1 million project replaced a 1913 dam that collapsed in 2008, forcing the closure of Mill Creek Park.