answers: Darién Gap
context: as the Inter-American Highway through Central America and Mexico where it splits into several spurs leading to the Mexico–US border. The concept of an overland route from one tip of the Americas to the other was originally proposed at the First Pan-American Conference in 1889 as a railroad; however, this proposal was never realized. The idea of building a highway emerged at the Fifth International Conference of American States in 1923. The first conference regarding construction of the highway occurred on October 5, 1925. Finally, on July 29, 1937, Argentina, Bolivia, Chile, Colombia, Costa Rica, El Salvador, Guatemala, Honduras, Mexico, </s> Great American Interchange The Great American Interchange was an important late Cenozoic paleozoogeographic event in which land and freshwater fauna migrated from North America via Central America to South America and vice versa, as the volcanic Isthmus of Panama rose up from the sea floor and bridged the formerly separated continents. Although there were earlier dispersals, probably over water, the migration accelerated dramatically about 2.7 million years (Ma) ago during the Piacenzian age. It resulted in the joining of the Neotropic (roughly South America) and Nearctic (roughly North America) ecozones definitively to form the Americas. The interchange is visible from </s> their trip. Pan-American Highway The Pan-American Highway is a network of roads stretching across the American continents and measuring about in total length. Except for a rainforest break of approximately , called the Darién Gap, the roads link almost all of the Pacific coastal countries of the Americas in a connected highway system. According to "Guinness World Records", the Pan-American Highway is the world's longest "motorable road". However, because of the Darién Gap, it is not possible to cross between South America and Central America with conventional highway vehicles. Without an all-terrain vehicle, it is necessary to circumnavigate this terrestrial
question: gap between north and south american road systems