Approximately 14,000 years ago, the Sammamish Valley was carved out by the Vashon Glacier as it melted and retreated. The continual flooding caused by seasonal storms and glacial melt deposited fertile topsoil throughout the valley. The glacial till found in upland areas supported lush forests of cedar, spruce, and fir with an abundance of wildlife.
 

The Sammamish Valley area was inhabited by the Simump Tribe prior to white settlement. The area saw an influx of white settlers in the 1870s. All transportation to and from the area was via the Squak Slough (today's Sammamish River). Squak means "swampy lowland" in the Simump language.
 

Bothell's early economy was driven by the lumber and shingle industries. Bothell was incorporated in 1909, about 20 years after the first plot was filed in the area by David C. and Mary Ann Bothell. According to one legend, there were so many people with the surname "Bothell" in town, the first postmaster said, "Let's call it Bothell." After Lake Washington was lowered in 1917 to construct the Lake Union locks, railroads and later highways became the primary methods of transportation to Bothell.