title: Pan-American Highway
context: The Pan-American Highway[1] is a network of roads stretching across the American continents and measuring about 30,000 kilometres (19,000mi)[2] in total length. Except for a rainforest break of approximately 160km (100mi), 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 stretch by sea.
question: What's the longest highway in the world?
answers: Pan-American Highway