Why can't you drive from North America to South America?

Because of the Darién Gap, a stretch of rainforest, swamp and mountains on the border between Panama and Colombia that no road has ever crossed. The Pan-American Highway runs about 30,000 km through North and South America, with one single exception: it stops at Yaviza in Panama and only starts again at Turbo in Colombia, roughly 106 km away. There is not even a primitive track in between.

Nature makes building one hard. The Colombian side is the delta of the Atrato River, a marsh at least 80 km wide; the Panamanian side is steep mountain rainforest. But the bigger reason is that many people do not want a road. Environmental groups worry about deforestation. Indigenous peoples such as the Embera-Wounaan and Guna fear losing the forests that feed them. And the US Department of Agriculture blocked funding in 1978 for a surprising reason: the jungle works as a quarantine wall. Central and North America have not seen foot-and-mouth disease in cattle since 1954, and the Gap is credited with keeping it out.

That has not stopped people from crossing. The first car crossing took three Brazilians in two Ford Model Ts a full decade, from 1928 to 1938, sometimes with the cars taken apart and carried by mules. Today, the Gap is one of the world's busiest migration routes, with more than 520,000 people walking through it in 2023.