- 1895 Rand U.S. Atlas - Washington
- 1909 map of Cowlitz County, taken from Cram's Washington State map (part of the USGenWeb Digital Maps Library project),
- Visit Cowlitz County Towns for a brief county history, and the description and history of many places that ever existed in Cowlitz County, including additional town-specific links.
- "Oregon, Washington and Alaska Gazetteer and Business Directory, 1901-1902" - all Cowlitz County entries from this Gazetteer and Directory.
- Transcription of the chapter on Cowlitz County from Robert A. Reid's 1912 book, "Puget Sound and Western Washington."
- Tramscription of Cowlitz County place names from Edmond Meany's "Origin of Washington Place Names", published in 1923.
- Want to know how that Cowlitz County location got its name? Check out the Tacoma Public Library's searchable list of placename origins.
- Check out the Cowlitz Co. Government site for links to government offices, tourism, and other info pertaining to Cowlitz Co.
- Cowlitz Co. Census Data - basic census data from the U. S. Census Bureau.