The true ancestor of the modern roller coaster is widely considered to be the "Russian Mountains" of the 17th and 18th centuries, which were massive ice-covered wooden slides. However, the first mechanical roller coaster to feature wheeled cars on a track was the Promenades Aériennes (Aerial Promenades) in Paris, opened in 1817. In the United States, the first commercially successful roller coaster was the Switchback Railway, designed by LaMarcus Adna Thompson and opened at Coney Island in 1884. It traveled at a top speed of only 6 mph and required passengers to climb a tower to board. By 2026, we look back at these gravity-powered curiosities as the birthplace of an industry that now features electromagnetically launched giants. While the Russian slides provided the concept of "gravity thrills," it was the Coney Island Switchback that proved roller coasters could be a profitable and repeatable theme park attraction, cementing Thompson's legacy as the "Father of the American Roller Coaster."