In 1844, American explorer John C. Fremont parked his horses at Big Springs, and his report to the government resulted in a mail route leading past the spot on its way to California.
American explorers helped in creating mail routes. 
mnli hypothesis: American explorers helped in creating mail routes.  premise: In 1844, American explorer John C. Fremont parked his horses at Big Springs, and his report to the government resulted in a mail route leading past the spot on its way to California.