Captain Randolph B. Marcy mapped this trail while in charge of a U.S. Army detail guarding citizens bound for the California Gold Rush. He disproved the theory that West Texas was a desert by traveling along a chain of springs and lakes known to the Comanche guide Manuel. In October 1849, he reached Big Spring, a site marked by many converging Indian trails, and from there went northeast toward the Red River. The route was later used by many emigrants and was followed by a transcontinental railroad and stagecoach line.