At a point where the Santa Clara River makes a bend to the east, the Spanish Trail left the river and climbed over the Beaver Dam Mountains, following a course practically identical with that of old U.S. Highway 91. On the west side of the Beaver Dam Mountains, on Utah Hill, the trail entered a forest of Joshua trees marking the eastern limits of the Mohave Desert. The Spanish Trail then left Utah, cut across the northwest corner of Arizona, and traversed southern Nevada, following the Virgin River for some distance. The good springs at Las Vegas stopped every caravan. The trail then crossed the Mohave Desert to southern California. Threading Cajon Pass, caravans reached San Gabriel and, finally, Los Angeles, at the end of the trail.
See: LeRoy R. Hafen, and Ann W. Hafen, Old Spanish Trail, Santa Fe to Los Angeles (1954); Eleanor F. Lawrence, "Mexican Trade between Santa Fe and Los Angeles, 1830-1948," California Historical Society Quarterly 10 (March 1931); John Adam Hussey, "The New Mexico-California Caravan of 1847-1848," New Mexico Historical Review 18 (January 1943); C. Gregory Crampton, "Utah's Spanish Trail," Utah Historical Quarterly 47 (Fall 1979).
C. Gregory Crampton