National Route 40
At a length of 5,224 km (3,246 mi), and stretching the whole mainland part of the country, the Ruta Nacional 40 is the longest national highway of Argentina and a popular travel itinerary. The southern end is at the South Atlantic coast and the road goes north following the Andes. The highway crosses remote and uninhabited parts of the country but also metropolitan areas like Mendoza and San Juan. The northern end is in La Quiaca at the border to Bolivia.
As the route goes through a variety of climatic zones and landscapes, driving its full length is still a bit of a challenge, even with a 4WD vehicle. Much of the road is still not paved; moreover, you may encounter paved sections that are under construction where vehicles need to drive on a temporary gravel track next to the road (such sections can be up to 20 km long).
Understand
Ruta 40 began as a connection between the few inhabited places in the strategically important border zone with Chile. Today it is a popular travel route and is marketed as such by the Argentinian tourism authorities. In practice, visitors only drive a part of the route; this is both due to the length of the highway and to the challenging conditions — one example of the latter is the Abra de Acay mountain pass where the road rises to 4,972 meters above sea level.
The route has been changed over the years. In the north there is still a debate which of the gravel roads should be named Ruta Nacional 40. In the south there is still a 100 km section between Cabo Vírgenes and Río Gallegos missing. Therefore the southern endpoint is given as Punta Loyola, a small port village near Río Gallegos.
Prepare
Plan at least two weeks for the journey, even more if you really want to enjoy the route. If you're in a hurry, the road can be driven in 8-10 days if there are no unforeseeable incidents. To get up to the Abra del Acay mountain pass, you would need an off-road vehicle, but luckily, there are alternative routes around this place where normal cars can be used. Despite the dry climate, there can be ice and snow blocking the road during the winter, and heavy rain can be a problem during the summer. Therefore, spring or fall are the best seasons for this journey.
Get in
There are multiple starting points, depending on where you wish to begin the journey. In addition to the places below, Mendoza is also a good option.
- Punta Loyola is a small harbor on the Atlantic coast near Rio Gallegos. You can drive there from Buenos Aires along the fully paved but sometimes heavily trafficked Highway 3. The distance is 2587 km to Río Gallegos, plus 37 km to Punta Loyola.
- La Quiaca can be reached from Buenos Aires by Highway 9 or Highway 34. Both highways have some four-lane sections, but most of them are busy two-lane highways. The distance is 1830 km. From Potosí in Bolivia you can get in along Highway 14 (paved).
- San Carlos de Bariloche is the way in from southern Chile for driving a part of the road towards north or south. From Osorno, cross into Argentina through the Paso Internacional Cardenal Antonio Samoré.
Go
(Cabo Vírgenes)-Punta Loyola-Río Gallegos
- Distance: 37 km (when the coastal road is finished, it will be 137 km)
- Road surface: asphalt
There are plans to extend the road along the coast to the southernmost part of the Argentinian mainland at 1 Cabo Vírgenes, though as of early 2011 nothing had materialized yet. Hence, the official starting point of the highway is 1 Punta Loyola, a small harbor town with some industries and a Norwegian shipwreck.
The cape is still possible to visit along a gravel road going out from Highway 3. There the Magellan road begins, and at the cape itself is a lighthouse and a Chilean border station.
Following the bay, the road enters 2 Río Gallegos, one of the biggest cities in southern Argentina.
Río Gallegos-Charles Fuhr(-El Calafate)
- Distance: 460 km
- Road surface: gravel until 28 de Noviembre, then asphalt until Tapi Aike, gravel until RP 5, asphalt until Calafate.
- Alternative routes: Ruta Provincial 5 Río Gallegos - El Calafate, entirely paved
Highway 40 overlaps Highway 3 for 35 km, then turns to the west and follows the Río Gallegos valley. The next built-up area is about 235 km away, from 3 El Turbio onwards. This is Argentina's biggest coal industry plant, though the production has been cut down since the 1990s when it was hit by the economical crisis. After the town of 4 28 de Noviembre, the road turns north and merges with highway 5 which it will overlap with until 5 Charles Fuhr.
Detour Torres del Paine
From Río Turbio you can take a detour into 2 Puerto Natales and on to the world famous 3 Torres del Paine National Park with its snow-covered summits.
Detour El Calafate and Los Glaciares
4 El Calafate is some 32 km west of the road, but the only major city in this region and as such the best alternative for finding a place to sleep. The city is a gateway to the 5 Los Glaciares National Park with glaciers and forested mountain landscape. The road to the national park is completely paved.
Charles Fuhr-Perito Moreno
- Distance: 656 km
- Road surface: until Tres Lagos asphalt, then more than 70 km gravel (possibly paved), then asphalt
- Alternative routes: Between Lago Cardiel and Riera there's a shortcut that used to form part of the Ruta 40 and is almost 50 km shorter than the current route. On the other hand, the current route through Gobernador Gregores is paved, but the shortcut isn't.
After Calafate the road follows the eastern bank of Lago Argentino, Argentina's second largest lake, and then passes Lago Viedma, the third largest. North of Lago Viedma there's a paved sideroad leading to 6 El Chalten. In the small town of 6 Tres Lagos you should really fill up, because the road will enter a very remote and desolate section. The gas station is at the junction of RP 31, a bit outside of the town.
The road crosses the Patagonian meseta (plateau) made up of harsh steppe, some hills and some small green valleys. This is a bad place to get problems with your car on this lonesome section of the route. The only notable town is 7 Gobernador Gregores with about 3,000 inhabitants and one gas station, though most people just drive past it. 150 km north there's a small roadhouse in the hamlet of 8 Bajo Caracoles (100 inhabitants). Then follows 9 Perito Moreno, a town with 4,000 inhabitants and all services travelers will need, including places to eat and sleep, a bank, a supermarket and a gas station. If driving between Los Glaciares and San Carlos de Bariloche, Perito Moreno is about halfway, so this is a good place to stop for the night.
Detour Perito Moreno National Park
7 Perito Moreno National Park 
can be entered from Tamel Aike, 89 km off the highway. With rudimentary infrastructure this might be the lonesomest national park of Argentina, but this also means you get to enjoy untouched lake and forest landscapes at the foot of the Andes without hordes of tourists.
Detour Cueva de las Manos
From Bajo Caracoles you can get to 8 Cueva de las Manos, one of the most important archaeological sites of Patagonia. It's named after the famous hand paintings, though there are also other cave paintings. 44 km off the highway.
Perito Moreno-Esquel
- Distance: 512 km
- Road surface: asphalt
- Alternative routes: old route 1S40 Río Mayo to José de San Martín, gravel, closer to the Andes
The landscape still stays desolate after Perito Moreno, but after 10 Río Mayo 110 km away the road is paved and some small towns follow: 9 José de San Martín, 11 Gobernador Costa and 12 Tecka (the latter has some natural attractions). Eventually you'll reach the city of 13 Esquel; with 40,000 inhabitants this is the biggest city since Río Gallegos. Esquel doesn't have many sights, but its very beautiful location among the Pre-Andes and range of available activities like hiking, mountainbiking and winter sports makes it a worthwhile place to stop.
Detours
For this section there's an alternative, more scenic route – the old highway which is nowadays named 1S40. It goes over 10 Alto Río Senguer, and the highlight is the mountain lake Lago Fontana.
From Esquel you can take a sidetrip to the Welsh town of 11 Trevelin.
Esquel-San Carlos de Bariloche
- Distance: 283 km
- Road surface: asphalt
The section between Esquel and Bariloche is probably the most touristy part of the southern Andes. The landscape comprises dense forests and many lakes. The only notable town here is 14 El Bolsón, a former hippie colony turned a popular destination for nature tourists. On the other hand 15 San Carlos de Bariloche at Lago Nahuel Huapí has grown into a big touristy city, and is a stepping stone to the 12 Nahuel Huapi National Park, the most visited in the country.
San Carlos de Bariloche-Chos Malal
- Distance: 585 km
- Road surface: asphalt
Past Bariloche the road edges the lake Nahuel Huapi, after that follows 16 San Martin de los Andes, a picturesque town at the Lake Lácar. It's a popular destination thanks to its access to the 13 Lanín National Park . The next big town is 17 Zapala (40,000 inhabitants), sitting among sandy hills. Around 18 Chos Mahal the road comes closer to the Andes again. Aside of a few historical buildings, Chos Mahal isn't that a spectacular town but it is a good access point to the mountains.
Chos Malal-Malargüe
- Distance: 334 km
- Road surface: until the border with Mendoza asphalt, then traces of asphalt until Malargüe.
After Chos Malal there's again a more lonesome section and at some places the road is in a bad condition. The volcanic and steppe landscape sees relatively few tourists yet has some things worth seeing like the volcano 14 Tromen. The only inhabited places here are the two small towns of 19 Ranquil and 20 Barrancas. Then follows the city of 21 Malargüe with a good selection of lodging.
Malargüe-Mendoza
- Distance: 350 km
- Road surface: asphalt, from Ugarteche on four-lane expressway.
- Alternative routes: a part of the section between El Sosneado and Pareditas along RN 144 and 143, asphalt.
More steppe follows, and just north of Malargüe you can take a sidetrip west to the huge sinkhole 15 Pozo de las Ánimas with the nearby ski resort 16 Las Leñas. The road then enters the Río Atuel valley and leads to 17 San Rafael, the second biggest city in the Mendoza province. Ruta 40 circumvents the city entirely. There are two parallel roads in this area marked as Ruta 40 on the map, the old dirt road and a new paved road. The dirt track is farther to the east.
After San Rafael there are some typical Cuyo landscape, even steppes interspersed by green and populated oases. After 22 Tunuyán comes 23 Ugarteche and the roads turns into four-lane expressway, and this is a sign that you're about to arrive in 24 Mendoza. Mendoza is the center of the Argentinian viticulture, and with a million inhabitants the fourth biggest metropolitan area in the country. It's also a starting point for trips to some of the highest mountains in the Andes including 18 Aconcagua.
Mendoza-San Juan
- Distance: 165 km
- Road surface: asphalt. Until Las Heras four lanes, then two lanes until Va. Media Agua, followed by four-lane toad to San Juan.
This relatively short stretch between two major cities is in a good condition, but traffic is heavy. The only notable sight here is the 19 sand desert near Lavalle, the only desert or that kind in South America. 25 San Juan is a oasis city and center for agriculture.
San Juan-Chilecito
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- Distance: 409 km
- Road surface: asphalt.
- Alternative routes: RN 150/RP456/RP491 Niquivil - Huaco via San José de Jáchal, asphalt.
Exiting the oasis at San Juan, the road goes through a dry, hilly landscape. 130 km north of the provincial capital is the second biggest oasis in the Jáchal valley with the city of 20 San José de Jáchal. The highway circumvents this city of 20,000 inhabitants; if you wish to enter, take RN 150 and then RP 456 and RP 491 to get back to highway 40 at 26 Huaco.
27 Villa Unión in La Rioja province is the next notable town, and an access point to Talampaya. Then follows the Cuesta de Miranda, where the road goes next to a spectacular gorge. After some minor hamlets you arrive in 28 Chilecito, the biggest city on the northern end of the route and a bit of a tourist hotspot. There are several attractions in the surroundings: old villages, rock formations and one of the world's highest mountain railways which nevertheless has been shut down.
Detour Talampaya
Off the highway is the 21 Talampaya National Park with interesting rock formations and palentological excavations. To get there, turn off at Villa Unión, drive about 70 km south along Highway 74 to Puerta de Talampaya. To explore the park in depth, you need to join a guided tour; in high season these tours often sell out.
Chilecito-Londres/Belén
- Distance: 218 km
- Road surface: asphalt.
North of Chilecito the road goes through the valley between Sierra de Velazco and Sierra de Famatina, some of the highest areas of the Andes with some mountains reaching up to 6,000 m above sea level. In the north of the La Rioja province, the valley turns into the highland of Campo de Belén. At the northern end of this highland is 29 Londres,the second oldest city of Argentina (after Santiago del Estero). This very calm and green city has two downtowns, but sadly there are few historical buildings left. A few kilometers further north is 30 Belén with a better selection of lodging and a center of weaving.
Londres/Belén-Santa María del Yocavil
- Distance: 172 km
- Road surface: asphalt.
Next up: some exciting landscapes. Right after Belén the road goes through a gorge, and after that the valley widens once again. A place worth stopping is 31 Hualfín a town surrounded by red rock walls. The highway goes 2,200 m above sea level, and descends into the Valle Calchaquí, one of the highlights of the journey. When you start seeing built-up areas, there are about 15 km left until 32 Santa María del Yocavil, the largest city in the valley. Santa María features a spectacular setting (if hardly any historical buildings), and there are many archaeological sites around the city.
Santa María del Yocavil-Cachi
- See also: Valles Calchaquíes
- Distance: 235 km
- Road surface: asphalt until San Carlos, then gravel until Cachi.
- Alternative routes: RP 357 from Santa María to Quilmes, asphalt.
After Santa María comes the most famous part of the Valle Calchaquí, a high-altitude valley at between 1,700 and 2,000 m above sea level. There are many things to see on a few kilometers. A worthwhile detour is to 22 Amaichá del Valle, a native American community of 4,000 inhabitants with a big museum presenting the local culture. A few kilometers further north is the ruins of 23 Quilmes, likely the best preserved precolumbian site in Argentina.
33 Cafayate is the tourist hub for the region and also a center of viticulture. The 24 Quebrada de Cafayate rock is also worth a little detour. After Cafayate the road once again becomes lonelier. There are several small towns with preserved colonial architecture like 34 San Carlos and 35 Molinos. The following bigger town, 36 Cachi, is the center of the northern part of the valley. Cachi has a well preserved downtown and there are several places to sleep. While the road to Cachi is passable in a smaller car, it is relatively challenging and can feature several detours into mud, sand, and ungraded gravel.
Cachi-San Antonio de los Cobres
- Distance: 145 km (over Abra del Acay), alternate route 100 km longer
- Road surface: asphalt until La Poma, from there a challenging to overwhelmingly challenging gravel road
- Alternatives: see below
After Cachi comes the hardest section of the route. Near 37 La Poma it the road starts going uphill in the valley. After this the road gets considerably steeper. An offroad vehicle is recommended, and the road can get impassable both in summer (due to rain) and winter (due to ice and snow). The road serpentines uphill to 38 Abra del Acay, at 4,972 m above sea level the highest mountain pass in Argentina and one of the highest in the world (there are higher ones in Himalaya). From there, the road downhill gets better and leads to the mining town of 39 San Antonio de los Cobres. A rather poor city, it is the main settlement in western Salta.
Detour Salta / Alternatives to Abra del Acay
There are two ways to circumvent Abra del Acay. Both these routes are around 100 km longer than going over the mountain pass. They will lead through the provincial capital of Salta with half a million inhabitants and one of the best preserved colonial old towns in Argentina.
The first alternative goes from Cafayete along Highway 68 through Quebrada de Cafayate (see above). From 1 El Carril or 2 Salta, to 3 Highway 51 that will take you San Antonio de los Cobres.
Alternatively, take RP 33 from Cachi, a route also known by the name 1 Cuesta del Obispo. This road passes an interesting gorge, and is passable without hassle at all times of the year. Also here, take the Highway 51 from El Carril or Salta.
San Antonio de los Cobres-La Quiaca
For the last stretch to La Quiaca, it has not been decided upon which of three possible routes should carry the label highway 40 so all three of them are described below:
Variant 1: Old route over Abra Pampa
- Distance: 290 km
- Road surface: gravel until Abra Pampa, then asphalt.
The 1 original highway 40 (carrying the name until 2005) goes north and is named Ruta 1V40, past the saline lake 2 Laguna Guayatayoc, crosses Puna and arrives in the town of 3 Abra Pampa with 10,000 inhabitants. There it joins with Highway 9 which leads to 40 La Quiaca. This is the shortest of the three routes, but it is unlikely that it will be officially labeled Ruta 40 again.
Variant 2: Via Cobres
- Distance: ca. 360 km
- Road surface: gravel until Santa Catalina, then asphalt
This routing is favored by the province of Jujuy. The route as it's planned is still under construction, so you need to take alternative routes for a part of this routing. From San Antonio, first take Ruta 1V40 north like in variant 1 above, 1 then Highway 52 to 2 Susques. From there the road continues north passing Puna villages including the mining town of 3 Mina Pirquitas which at 4,271 m above sea level is the highest in the country. The route almost reaches the Bolivian border, then turns east before arriving in La Quiaca. Before that you can take a sidetrip to 4 Santa Catalina, Argentina's northernmost town, with a colonial 17th century church.
Variant 3: Through Western Salta
- Distance: 380 km
- Road surface: bad gravel road until Susques, better gravel until Santa Catalina, then asphalt
This stretch is nowadays the "official" highway 40 and is favored by the province of Salta which sees it as a way of developing the west of the province. From San Antonio it overlaps with Highway 51 and goes towards Chile for 10 km or so, after which this 1 Ruta 40 veers off north towards Susques and becomes poor enough that it's better driving by an offroad vehicle. In Susques it joins the route described as variant 2 above.
Stay safe
As already mentioned, some of the sections are better driven with a vehicle suitable for off-road driving or even driving as a group of multiple vehicles. Unlike for example remote parts of Brazil, highwaymen are unheard of here. Such asphalt pirates (piratas del asfalto) do exist on a smaller scale in Argentina, though they operate on busier roads and almost exclusively target trucks.
Fill up whenever you can, especially in Patagonia. Firstly, there's no guarantee that the next gas station has fuel available, moreover the mountainous terrain means higher fuel consumption than you might expect.
Go next
If you after the long journey have arrived at the Bolivian border and still are looking for more to see, take Bolivian Highway 14 to Potosí. From there you have all of Bolivia's attractions ahead of you, and you can continue onwards to other South American countries such as Brazil, Paraguay or Peru. To bring a car to Bolivia, a Carnet de Passages is required and you should obtain this document beforehand — obtaining it on the border is possible but the bureaucracy often takes several days.
In the southern end, you can continue to Tierra del Fuego with its temperate rainforests, lakes, landscapes and Ushuaia, the world's southernmost city. Also the south of Chile (which you need to pass through anyway) is worth a visit.