When western Montanans go away for a weekend, there’s a pretty good chance they’re headed to Flathead Lake. At 28 miles long, 7–8 miles wide, and more than 300 feet deep, it’s the largest natural freshwater lake west of the Mississippi. The lakeshore is dotted with campgrounds and summer cabins, many owned by the same families for years.
Flathead Lake fills a trench carved by glaciers during the Pleistocene Epoch. A terminal moraine at the foot of the lake divides the Flathead Valley from the Mission Valley to the south.
Three upper forks of the Flathead River join above Kalispell  to pour into Flathead Lake. The North Fork originates in southeastern British Columbia , the Middle Fork rises in the northern part of the Bob Marshall Wilderness Area  (near the southern edge of Glacier National Park ), and the South Fork flows from the southeastern region of the Bob Marshall Wilderness Area via Hungry Horse Reservoir .
Steamboats ran on Flathead Lake in the late 1800s and early 1900s. Their route was from Demersville (a now-defunct town on the Flathead River, halfway between Kalispell and Flathead Lake) down to Polson .
The first white settlers on the eastern banks of the lake arrived in 1891 and quickly hit on the idea of growing cherries there. Homesteading started in earnest around 1910, when reservation land became available to non-Indians under the Dawes Act. Fruit orchards were established all along the eastern shore of the lake. Although they’re subject to periodic killing frosts, Flathead Lake’s cherry trees are productive enough to supply farm stands and roadside vendors around the region.