Billboards dot the roadside along most American highways today, making it difficult to imagine a time when highway signs not only drew close attention but even created a sensation. The following aerial views of two American tourist traps show the importance of highways in delivering visitors. While Wall Drug began as a small-town pharmacy with a Main Street storefront, South of the Border sprouted as a stop along U.S. Highway 301. Although both attractions built their reputations through shrewd advertising along hundreds of miles of roads, as detailed by historians Troy Henderson and Meeghan Kane in American Tourism: Constructing a National Tradition, the route of Interstate highways helped assure their continuation even as countless other roadside attractions closed after being marooned when the freeways whisked…