Renton is located in a geographic sweet spot within King County, bordered by Lake Washington to the north, the Cascade foothills to the east, and neighboring cities like Tukwila and Kent to the west and south. Its defining geographic feature is the Cedar River, which originates in the Cascade Mountains and cuts directly through the heart of Renton before emptying into Lake Washington.
The city rests in the Puget Sound lowlands, characterized by a mix of rolling topography and lush, evergreen-dominated landscapes typical of the Pacific Northwest. Before the opening of the Lake Washington Ship Canal in 1916, Lake Washington drained out through the Black River in Renton. The lowering of the lake caused the Black River to dry up, fundamentally altering the local geography and making the Cedar River the primary waterway in the city.