Approximately 700 mi (1,100 km) long, the trail ran through areas of high mountains, arid deserts, and deep canyons.

The eastern parts of what became called the Old Spanish Trail, including southwest Colorado and southeast Utah, were explored by Juan Maria de Rivera in 1765.

Franciscan missionaries Francisco Atanasio Domínguez and Silvestre Vélez de Escalante unsuccessfully attempted the trip to California, which was just being settled, leaving Santa Fe in 1776 and making it to the Great Basin near Utah Lake before returning via the Arizona Strip.

Other expeditions, under another Franciscan missionary, Francisco Garcés, and Captain Juan Bautista de Anza, explored and traded in the southern part of the region.

[7] Word spread about Armijo's successful trade expedition, and some commerce began between Santa Fe and Los Angeles.

However, in 1830, due to resumed hostilities with the Navajo, the Armijo route west to the Colorado River Crossing of the Fathers was not practical.

California had many horses and mules, many growing wild, with no local market, which were readily traded for hand-woven Indian products.

The return party would usually leave California for New Mexico in early April to get over the trail before the water holes dried up and the melting snow raised the rivers too high.

Low-scale emigration from New Mexico to California used parts of the trail in the late 1830s when the trapping trade began to die.

Some raiders attacked the California ranchos for horses and captives to sell in the extensive Indian slave trade.

Native Americans along the route were at risk of being taken captive, especially the women and children of the Paiute, who were sold as domestic servants to Mexican ranchers and other settlers in both California and New Mexico.

After 1848 numerous Mormon immigrants began settling in Utah, Nevada, and California all along the trail, affecting both trade interests and tolerance for the slavery of American Natives.

From the San Juan, they entered the Four Corners area, and passed north of the Carrizo Mountains to Church Rock, east of present-day Kayenta.

At the Colorado River (then called the Rio Grande), the travelers forded at the Crossing of the Fathers above present-day Glen Canyon Dam.

They traveled west parallel to the river, over difficult terrain in the Black Mountains, to avoid the deep narrow gorge of Boulder Canyon, to the riverside oases of Callville Wash and Las Vegas Wash. Armijo waited there for his scouts to return, especially Rivera who had visited the Mohave villages downriver before.

Perhaps because the Mohave had been antagonistic to parties of mountain men in recent years, or to save time, Armijo attempted a short cut route southwest to the mouth of the Mojave River.

Probably at Summit Valley at the top of the river east of Cajon Pass, they met vaqueros of the San Bernardino de Sena Estancia who had extra food.

First traveled in 1830 by a party led by William Wolfskill and George Yount, this route ran northwest from Santa Fe through southwestern Colorado, past the San Juan Mountains, Mancos, and Dove Creek, entering Utah near present-day Monticello.

Later caravans could alternatively follow the Armijo Route diverting southwestward from the Colorado at Las Vegas Wash, to Resting Springs and to the Mojave River where it joined the Wolfskill/Yount Route, following that river upward to and over the San Bernardino Mountains through Cajon Pass, Crowder Canyon and lower Cajon Canyon and across the coastal valleys to Mission San Gabriel and Los Angeles.

Caravans then headed west to today's Saguache, crossing over the Continental Divide at Cochetopa Pass, and then through present day Gunnison and Montrose to the Uncompahgre Valley.

[12] The western portions of the Old Spanish Trail could only be used semi-reliably in winter when rains or snows deposited water in the desert.

On April 20, 1844, following the advice of his guide, John C. Frémont intercepted this route to the river, riding east southeast from Lake Elizabeth, north of the San Gabriel Mountains.