Continental Divide

I-40 crosses the North American Continental Divide at Campbell Pass, a broad, low saddle in McKinley County in western New Mexico. This is not a peak. The road tops out at a wide east-west valley, which is the whole reason the railroad chose this line in the 1880s and why Route 66 and then I-40 followed it. The headline elevation is 7,275 ft (Wikipedia, Interstate 40 in New Mexico), and the roadside historic marker reads 7,245 ft. Mount Taylor, an 11,305-ft stratovolcano, sits to the east, but the highway itself never climbs anything like that.

The crossing falls between Gallup, about 25 miles to the west, and Grants and Thoreau to the east. Right at the divide sits the unincorporated community of Continental Divide (ZIP 87312), with a 2020 census population of 187 (Wikipedia, Continental Divide, New Mexico). For a trucker this is the high point of the I-40 run across western New Mexico. The NM segment enters from Texas near 4,500 ft and climbs past 7,000 ft near the divide (RMS Truck Insurance I-40 corridor guide), which the same guide sums up plainly: at that altitude your engine makes less power, and you are dealing with mountain weather, not desert weather.

One thing to keep straight. The Continental Divide climb is long and gradual, not a steep grade. The steep, sustained pull on I-40 in New Mexico is Tijeras Canyon east of Albuquerque, roughly mile 167 to 177, and that is where the brake-fade problems cluster. That is a separate place about 150 miles east of the divide. Do not run your pre-trip plan for one as if it were the other.

• Campbell Pass is a broad valley crossing of the Continental Divide in McKinley County, western New Mexico, not a mountain summit (Wikipedia, Interstate 40 in New Mexico)
• Headline elevation 7,275 ft; the roadside historic marker reads 7,245 ft (Wikipedia, Interstate 40 in New Mexico; theroute-66.com)
• Mount Taylor, an 11,305-ft stratovolcano, rises to the east, but I-40 itself stays in the valley (Wikipedia, Interstate 40 in New Mexico)
• The crossing sits between Gallup, about 25 miles west, and Grants and Thoreau to the east
• The community of Continental Divide (ZIP 87312) had a 2020 census population of 187 (Wikipedia, Continental Divide, New Mexico)
• New Mexico has no mandatory chain law; statute 66-3-847 permits chains and studded tires but does not require them (NM Stat. 66-3-847)
• The railroad through Campbell Pass was built for a very moderate grade, about 21 feet per mile, or 0.4%, and I-40 follows the same corridor (theroute-66.com)

There is no chain-control season here, because New Mexico does not run one. The state has no mandatory chain law and no posted chain levels like Colorado or California. Statute 66-3-847 permits chains of reasonable proportions and studded snow tires when you need them for traction on snow or ice, but it does not order anyone to chain up (NM Stat. 66-3-847). There is also no DOT-designated chain-up area or brake-check station at the Continental Divide. So the practical rule is simple: when a winter storm makes the road unsafe, NMDOT does not call for chains, it closes the road. Closures are case-by-case decisions by NMDOT and law enforcement, with no fixed dates and no published snow-depth or wind trigger. They get pushed to the signs and to NMRoads / NM 511. Check that before you run it.

Campbell Pass earned its place because of grade, not scenery. Around 1880 to 1881 it was selected as the route for the original main line of the Atlantic and Pacific Railroad, which later became part of the Atchison, Topeka and Santa Fe. Crews chose it for a very moderate grade, about 21 feet per mile, or 0.4%, and built a station near the summit called Gonzales (Wikipedia, Campbell Pass; theroute-66.com). The settlement at the crossing changed names more than once: Continental Divide in 1884, then Summit in 1895, then Gonzales from 1910 to 1936, before it went back to Continental Divide (theroute-66.com).

The highway story runs on the same line. The corridor was designated NM State Highway 6 in 1914, and an 8.6-mile stretch was finished as a divided four-lane road in 1951 (Legends of America). U.S. Route 66 went through Campbell Pass in 1926, and I-40 is its successor along the same corridor (Wikipedia, Campbell Pass). Railroad, Route 66, and Interstate all picked the same low saddle for the same reason.