Ruta Nacional 40 Paso de Agua Negra International Route
Sky-high Andean border crossing at 4,765 meters
The Paso de Agua Negra sits at 4,765 meters above sea level, making it one of the highest drivable passes in South America. This remote border crossing follows pre-Columbian trade routes through the high Andes, passing abandoned mining camps and salt-crusted lagoons where flamingos feed in the shadow of 6,000-meter peaks. The route branches off RN40 near Iglesia, climbing through the Cordillera de los Andes via switchbacks carved from solid rock, with the final approach crossing the Salinas Grandes salt flat.
This is expert-level high-altitude driving requiring serious preparation and mechanically sound 4WD vehicles. Altitude sickness hits hard above 4,000 meters, and weather changes without warning year-round. Best attempted November through March when snow clears, but even summer crossings demand tire chains, extra fuel, and emergency gear. Border formalities on the Chilean side can take hours, and there’s no fuel for 200+ kilometers. What you get is bragging rights to one of the world’s most spectacular and punishing mountain crossings.
Trail Specs
| Difficulty | Expert |
|---|---|
| Trail Type | Overland Route |
| Surface | Mixed |
| Features | High Altitude, Historic, Remote, Scenic |
| Length (miles) | 118 mi / 190 km |
| Duration | 1-2 days |
| Max elevation (ft) | 15633 ft |
| Best season | November-March |
| Minimum vehicle | Stock 4WD high-clearance |
| Nearest town | Iglesia, San Juan |
| Land manager | Dirección Nacional de Vialidad |
| Permit required | No |
| Cell service | None |
| Water crossings | No |
| Dispersed camping | Yes |
| Start coordinates | |
| End coordinates | |
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Location
Trail Conditions
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Frequently asked questions
Can a stock 4WD high-clearance vehicle handle Paso de Agua Negra, or do I need a built rig?
A stock 4WD high-clearance vehicle can make it, but the route's loose rock, steep switchbacks, and 4,765-meter summit will punish anything marginal. Mechanically sound brakes, a healthy cooling system, and all-terrain tires are non-negotiable at this altitude — a breakdown here is a serious problem.
When is Paso de Agua Negra actually passable, and does snow close it outside of summer?
November through March is the reliable window. Outside of that, the pass is frequently closed by snow and ice, and Argentine and Chilean authorities can shut the border with zero notice even mid-season. Check with Gendarmería Nacional before you leave Iglesia — don't assume it's open.
Do I need permits or special documentation to cross into Chile at Agua Negra?
Yes — this is an international border crossing. You need a valid passport, vehicle title, and a vehicle authorization document (known as a 'libreta de pasos') issued at the border. Certain food, plant, and animal products are confiscated by Chilean customs (SAG). Budget extra time; border processing here is not fast.
What's the hardest section of the route and what should I expect?
The Argentine-side switchbacks approaching the 4,765-meter summit are the crux — tight, loose-surfaced hairpins with significant exposure and no guardrails. Altitude sickness is a real threat above 3,500 meters, and the thin air will tank your engine's power output noticeably. Don't rush it, and know your AMS symptoms before you go.
Is there any fuel available along the route, or do I need to carry extra?
There is no fuel between Rodeos (San Juan side) and Vicuña (Chile side) — roughly 190 km of nothing. Fill the tank completely in Rodeos and carry a jerry can; this route combined with high-altitude fuel consumption will eat your range faster than expected.
Trail track
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