The United States foresees an estimated shortage of between 37,800 and 124,000 physicians by 2034, including shortfalls in both primary and specialty care. Currently, more than 83 million people in the US live in areas in which access to a primary care...

In the early 19th century, The Mauch Chunk Switchback Railway became the prototype for roller coasters in the United States. It was a gravity railway built in 1827 to haul coal about nine miles between coal mines. Gravity forced the cars carrying one-and-a-half...