There are numerous border crossings from neighboring Bolivia, Brazil, Chile, Paraguay and Uruguay. Border formalities are generally straightforward as long as all your documents are in order.
La Quiaca to Villazón Many buses go from Jujuy and Salta to La Quiaca, where you walk across a bridge to the Bolivian border.
Aguas Blancas to Bermejo From Orán, reached by bus from Salta or Jujuy, take a bus to Aguas Blancas and then Bermejo, where you can catch a bus to Tarija.
Salvador Mazza (Pocitos) to Yacuiba Buses from Jujuy or Salta go to Salvador Mazza at the Bolivian border, where you cross and grab a shared taxi to Yacuiba.
There are numerous crossings between Argentina and Chile. Except in far southern Patagonia, every land crossing involves crossing the Andes. Due to weather, some high-altitude passes close in winter; even the busy Mendoza–Santiago route over RN 7 can close for several days (sometimes longer) during a severe storm. Always check road conditions, especially if you have a flight scheduled on the other side of the mountains. The following are the most commonly used crossings:
Bariloche to Puerto Montt This border crossing over the Andes to Chile is usually no fuss; a popular ‘tour’ crossing is the famous, scenic 12-hour bus-boat combination. It takes two days in winter.
El Calafate to Puerto Natales and Parque Nacional Torres del Paine Probably the most beaten route down here, heading from the Glaciar Perito Moreno (near El Calafate) to Parque Nacional Torres del Paine (near Puerto Natales). Several buses per day in summer; one to two daily in the low season.
Los Antiguos to Chile Chico Those entering Argentina from Chile can access the rugged RN 40 from here and head down to El Chaltén and El Calafate. Best in summer, when there’s actually public transportation available.
Mendoza to Santiago The most popular crossing between the two countries, passing 6962m Aconcagua en route.
Salta to San Pedro de Atacama (via Jujuy, Purmamarca and Susques) A 10-hour bus ride through the altiplano with stunningly beautiful scenery.
Ushuaia to Punta Arenas Daily buses in summer, fewer in winter, on this 10- to 12-hour trip (depending on weather conditions), which includes a ferry crossing at either Porvenir or Punta Delgada/Primera Angostura.