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 stretch by sea.
U.S. Route 16 in South Dakota
US 16 is also known as Mount Rushmore Road in western South Dakota. The highway enters South Dakota east of Newcastle, Wyoming. It travels near Jewel Cave, the third-longest cave in the world. The highway goes through the city of Custer and shares alignment with US 385. East of Hill City, US 16 splits off US 385. It then becomes a four-lane divided highway, with the two roadways separated by up to in some places, including the old gold-mining town of Rockerville, South Dakota, which is contained entirely in the median of US 16. In Rapid City, US 16 follows Mount Rushmore Road to a concurrency with SD 44 (Omaha Street) to the southern terminus of I-190. US 16 stays concurrent with I-190 until both highways end at I-90.