The Old Spanish National Historic Trail served as an overland trade route between 1829 and 1848, which connected Santa Fe, New Mexico, and Los Angeles, California, when these lands were part of the Mexican frontier. Caravans organized by New Mexico businessmen and Europeans coming west to pursue their fortunes were guided along the trail network by Native Americans and fur trappers. Most caravans brought northern New Mexico woolen goods and farm products to California to trade for horses and mules. The trail fell into disuse after United States accessed the territories. The Old Spanish National Historic Trail is jointly administered by the National Park Service and the Bureau of Land Management.
The Old Spanish National Historic Trail crosses New Mexico, Colorado, Utah, Arizona, Nevada, and California in three routes: the Armijo Route, pioneered in 1829; the Main Route, which saw most of the historic trail travel; and the Northern Route, which was used as an alternate route when inclement conditions were expected on the mountain passes of the Main Route, and potentially for more nefarious reasons. The three routes span some 2,700 miles. Where the trail has been preserved, through its presence in historic documents or through its continued use after 1848, the original mule trace has most often been overlain by wagon roads, then later - gravel roads and paved highways. Many miles of the original routes still retain their historic landscape character.
(Modified from National Park Service documents)