Long-distance buses are the backbone of South American travel, and many of them are genuinely excellent. Argentina, Chile, and Brazil operate luxury overnight services with fully reclining seats (look for "cama" or "leito" class), onboard meals, and wine. In Bolivia and Peru, bus quality varies wildly — you'll find everything from modern coaches to rattling minibuses on mountain switchbacks. Book through reputable companies, travel during daylight in the Andes when you can, and always keep your valuables close.
Flying has become much more accessible. Budget carriers like JetSmart, Sky Airline, and Gol now connect major cities at reasonable prices if you book ahead. For covering big distances — say, Buenos Aires to Bogota — flying saves days of overland travel. Domestic flights are especially useful in Brazil, where distances are staggering, and in Colombia, where mountains make overland routes slow.
Trains are largely a thing of the past in South America, but the few remaining routes are memorable. The train from Cusco to Aguas Calientes (Machu Picchu) is one of the continent's great rides. Ecuador has restored scenic rail routes through the highlands. Bolivia's Oruro-to-Uyuni train crosses the altiplano in a way no bus can match. Don't plan a trip around rail, but do take a train when the opportunity comes up.
Driving is straightforward in Argentina, Chile, and Uruguay, where roads are generally well-maintained and signage is decent. In the Andes and Amazon regions, it's a different story — unpaved roads, landslides in the rainy season, and aggressive local driving habits make self-driving stressful. Car rental is expensive almost everywhere. If you want to drive, Patagonia is the place to do it: the open roads and vast landscapes reward having your own wheels.
One thing you cannot do is drive from Central America to South America. The Darien Gap — a roughly 100-kilometer stretch of dense jungle between Panama and Colombia — has no road. Overlanders ship vehicles by cargo boat or ferry from Panama to Cartagena or fly across. Some adventurers trek the Gap on foot, but it's dangerous, expensive, and takes days. For most travelers, a short flight from Panama City to a Colombian city is the sensible way through.