In 1971, by agreement of all North and South American countries, it was agreed that all countries would work towards completing their respective sections of the Pan american highway.
Thus the USA took on the challenge of completing a road through the Darien Gap.
In 1974, the USA gave up.
The Darién Gap crosses 10,000 square miles of untamed jungle shared by Panama and Colombia. It’s wet to the point of swampy in areas. Where it’s not too wet to drive, guerrilla groups operate in the jungle.
Both countries try to block tourists from entering, since the dangers are too great. There is no road, and it’s doubtful that even a four-wheel drive could get through the jungle-swamp. Well prepared hikers have trouble.
Disease, dangerous animals, deadly insects, gunfire…
To this day, the Darien Gap is so impassable that *viruses* prevalent in South American have not crossed to North America or vice-versa.
A team of adventurers in a Land Rover succeeded in 1960 to drive through though.. Their purpose was to promote the idea of completing the Pan-American Highway. 1960: Trans Darien Expedition
Another group did it again 1971. in both cases, it took them 5 months JUST to cross the Darien Gap. And there seem to be other similarities to their travel - namely that they did a lot of pushing and pulling to get the vehicle through. 1971/72: Range Rover Darien Gap - Range Rover Classic.
The 1971 expedition was a British Army expedition, comprising a crew from the 17th/21st Lancers led by explorer Colonel John Blashford-Snell, using British Range Rovers to travel from Alaska to Tierra Del Fuego. The Darien Gap busted NINE back axles in the Range Rovers, leading Rover Ltd to parachute in replacements and an engineer; and to completely redesign the back axle. Some of the story is told here: Range Rover Darien Gap.
With each of the vehicles, also walked a crew of eight Engineers who were responsible
for the digging, laying ladders, cutting trees, winching etc to keep the Range Rover's moving through.
The expedition had radio contact with the two bases outside the Darien Gap. The Army Air Corps had a Beaver aircraft for supply of petrol, mail, supply materials needed in the jungle. The goods were dropped with parachutes from the plane at places market by smoke signal, flares or balloons in the forest. The overall fuel consumption was approximately 1 mile per gallon and the average distance a day through the Darien Gap were only 2 miles.
Before the expedition hit the Colombian border, they found the wrecks of the Chevrolet Corvairs from the American expedition in 1962 strewn across the jungle! The mission with the Chevrolet-led expedition named "Daring the Darien" was to drive 3 Corvairs to the border of South America, and the boundary stone at the border between Panama and Colombia marks the beginning of South America.
All did not make it.
Despite the Americans having made a propaganda short film of their "succesful" exploits with saloon Chevrolet. The cars have been found strewn across the jungle.
Pan-American Highway is by no means a “highway” for much of its route. It turns into a dirt road going through most Latin America towns, and doesn’t get much better out of town once you get to Guatemala, the condition of the highway is the least of your worries.