The river rises on the east side of the Sangre de Cristo Mountains, around above sea level, in remote southwestern Las Animas County, Colorado, roughly north of the New Mexico border. An upper tributary of the Vermejo River heads around 12,000 feet in elevation in the Culebra Range and has a confluence with the Canadian south of Maxwell, New Mexico. Overall, the meandering course is from its origin to its confluence with the Arkansas River. The main tributaries are the North Canadian, Little, and Deep Fork Rivers.