Halloran Summit

Halloran Summit sits on Interstate 15 in San Bernardino County, out in the Mojave Desert northeast of Baker, California. This is the main truck route between the Los Angeles basin and Las Vegas, so most of the freight that runs that lane crosses here. The summit road is Exit 265. Halloran Springs Road is Exit 259, and Cima Road, which gets you into Shadow Valley and the Mojave National Preserve, is Exit 272.

The elevation depends on which source you read. Wikipedia and AARoads put it at "over 4,000 feet." FoxRVTravel lists 4,700 feet. The honest answer is somewhere around 4,600 to 4,700 feet. One thing to keep straight: this is not the same as Mountain Pass, a separate and slightly higher summit at about 4,730 feet farther northeast toward the Nevada line. Several writeups blend the two, and they are different climbs.

What makes drivers pay attention here is the grade and the isolation. The I-15 grade in this stretch runs up to 6%. Eastbound you climb roughly 6% for about 10 miles cresting toward the summit. Westbound and southbound toward Baker the descent is gentle for the first couple of miles, then steepens to as much as 6% for around 17 miles, dropping from the high desert plateau down to Baker at roughly 930 feet. That is a fall of well over 3,000 feet, and there is not much out here between services. Add open-desert crosswinds, blowing dust off the dry playas, and the occasional winter snow event, and you have a corridor that demands cool brakes and a full tank.

• Halloran Summit is on I-15 in San Bernardino County, Mojave Desert, northeast of Baker, CA; the summit road is Exit 265 (AARoads; Wikipedia)
• Summit elevation is roughly 4,600 to 4,700 ft; sources say "over 4,000 ft" (Wikipedia/AARoads) and 4,700 ft (FoxRVTravel)
• The grade reaches up to 6%, about 10 miles climbing eastbound and up to 17 miles on the descent toward Baker (FoxRVTravel; gribblenation)
• The corridor drops from the high point to about 930 ft at Baker, well over 3,000 ft of descent (AARoads; gribblenation cites near 900 ft)
• I-15 adds a third truck climbing lane up Halloran Summit between Exit 247 and Exit 265 (AARoads)
• This is the main freight route between the LA basin and Las Vegas/Primm; about 45 miles of isolated desert lies between Baker and Primm, NV (AARoads)
• Do not confuse it with Mountain Pass, a separate summit at about 4,730 ft farther northeast (AARoads)

Caltrans does not publish fixed chain-control dates for this part of I-15. Control here is weather-driven, posted ad hoc during winter storms rather than as a permanently named control zone. Snow events have hit in the December through February window. The control "closes" when the storm clears and Caltrans pulls the posting, which can be a matter of hours, not a fixed end-of-season date. One honest caveat: Caltrans chain pages name other passes such as Cajon Pass on I-15, but they do not name a permanent Halloran Summit chain-up area or mile marker, so do not expect a posted control zone here the way you would on a named mountain highway.

Before the freeway, the old two-lane US 91/466 climb out of Baker toward Halloran Summit earned the name "Bloody Baker Grade" for its accident and fatality rate. The full freeway alignment changed that. The roughly 25-mile stretch from the eastern edge of Baker up toward Cima Road opened as a freeway version of US 91/466, later I-15, reported in the September/October 1961 edition of California Highways and Public Works (gribblenation).

Even on the modern Interstate, weather still shuts this corridor down from time to time. On February 6, 2019, snow and ice closed I-15 northbound at Cima Road, about 13 miles north of Halloran Springs, and southbound at the NV/CA state line. CHP escorted traffic, a jackknifed big rig blocked lanes near Nipton Road, and another semi went onto its side at Halloran Springs; northbound reopened around 9:05 a.m. (news3lv). Dust is the other recurring closer. On November 21, 2023, a dust storm dropped visibility to near zero on I-15 near Primm at the CA-NV border, CHP closed a section, and NWS Las Vegas issued a Dust Storm Warning; North Las Vegas Airport clocked a peak gust of 62 mph (Fox Weather; 8newsnow; NWS Las Vegas).