- Snohomish County — Thumbnail History (historylink.org)
Snohomish County, formed on January 14, 1861, was originally part of Island County. It covers 2,098 square miles, ranging from the Cascade Mountains to Puget Sound. It is bordered by Skagit County to the north, King County to the south and Chelan County to the east. Forest constitutes 68 percent of the county’s land, and Mt. Baker National Forest and 10,436-foot Glacier Peak lie within its boundaries…