Officially incorporated on December 19, 1898, Sedro-Woolley was formed from two neighboring rival towns known as Sedro and Woolley.
The area formerly known as Sedro was first settled in 1884 by Mortimer Cook. He bought and cleared 34 acres along the Skagit River, near what is now Riverfront Park. He ran a general store there, opened a shingle mill and was the town's first postmaster.
Cook originally intended to name his town "Bug" due to the notable presence of mosquitos, however his wife protested, so he opted for "Cedra," the Spanish word for cedar, which then proceeded to become the town's official name. However, in an amusing fluke in local history, the correct spelling and pronunciation of this word was lost in the process and somehow became "Sedro."
The area that became known as Woolley (just north of Sedro) was first settled in 1890 by Philip A. Woolley. The town of Woolley included a coal processing plant employing approximately 2000 people.
Known as the gateway to the North Cascades.