During the 19th century the United States underwent a dramatic westward expansion, but perhaps no single event stimulated this mass migration more than the 1848 discovery of gold at Sutter's Mill in California. Hundreds of thousands of Americans were struck with "the fever" responsible for perhaps the single greatest mass migrations in American history. The majority of gold seekers followed the established Oregon Trail, which then took on the name of the "Forty-Niner" or "California" trail.

Coming from the eastern states tothe starting points of Independence, or St. Joseph, Missouri, or Council Bluffs, Iowa, fortune hunters entered Thayer County near presentday Alexandria and followed the Big Sandy Valley, where water, wood, and grass were available. After crossing the Big Sandy near Belvidere, the trail proceeded in a south-westerly direction to the banks of the Little Blue River. After the establishment of Thompson's Station, a few miles south of Belvidere, the trail followed the Eighteen-Mile Ridge across Thayer County. The Pony Express, freighters, overland stage companies and the railroads later used the route.

The call to adventure, possible riches, or a new home in a new land, encouraged people of all backgrounds to attempt the arduous trek to California. These hardy pioneers struggled against disease, heat, lack of water and Indian threats to find their own personal pot of gold at the end of the Forty-Niner Trail.

- Nebraska State Historical Society Marker