Río Blanco is a narrow spot in the Aconcagua valley where the mountains close in and the road to Argentina begins to climb in earnest. It sits at fourteen hundred metres, thirty kilometres above Los Andes, and its significance is geographical as well as practical. Here two rivers, the Juncal and the Blanco, meet to form the Aconcagua, which runs west through the valley to the Pacific near Concón. The place has been a gateway for centuries, used by Indigenous traders, then by Spanish colonists, and later by the armies that crossed the mountains during the independence wars.
The modern road, Route 60, follows the same route, and it is the main link between Santiago and Mendoza, so it carries a heavy flow of lorries. It is also a good riding road, with smooth tarmac, strong gradients and a constant sense of the mountains closing in. The valley walls are rust-red and ochre, scattered with cacti and dry scrub, and the river runs fast and cloudy at the bottom. The mining operations of Andina, a large copper mine in the high mountains, are a presence in the valley, and you will see the mine's buses and trucks moving up and down.
The Transandine Railway also ran through here. Opened in the early twentieth century, it climbed from the Chilean side to a long tunnel under the pass and on to Mendoza, an astonishing piece of engineering that carried passengers and freight until the 1980s. Sections of the old track and a few bridges can still be seen alongside the road. It is a good place to imagine how remote and difficult this crossing was before engines.
Fuel and food are best done in Los Andes, a town of nearly sixty thousand people with every kind of station, shop and restaurant, thirty kilometres down the valley. There is little above Río Blanco, so fill up before you climb, and take a warm layer because the temperature drops quickly. The road is open most of the year, but heavy snow in winter closes it for periods, and the border can be shut when conditions are bad, so check before you ride. The best weather is in spring and autumn, when the air is clear and the traffic is lighter.