1846 - 1847
The US Congress declared war against Mexico in May 1846. A month later, General Stephen W. Kearny's Army of the West left Fort Leavenworth, and by the end of August his forces had gained control of New Mexico. Indian raids made the Cimarron Route increasingly dangerous, so most trail traffic was diverted to the Mountain Route. Trail length from Independence to Santa Fe via the Mountain Route = 844 miles.