What Are CFCs? CFCs are short for the compound, chlorofluorocarbon, which contain carbon, chlorine, and fluorine. Chlorofluorocarbons are more commonly referred to as CFCs or, when used for refrigeration, CFCs are also known as freon. Developed in the 1930s as a safe alternative to ammonia, usage of CFCs grew rapidly because of its usefulness and convenience throughout most of the 20th century.
Great Northern Railway 1893-1925 The first route over the pass was a series of switchbacks, with grades of up to 4 % on the West side and 3.5% on East side, was completed on January 6, 1893 (see photos below). To traverse a switchback the train has to travel to the end of the dead end spur, then the switch is thrown and engine reverses
The First Transcontinental Railroad in North America was built in the 1860s, linking the well developed railway network of the East coast with rapidly growing California. The main line was officially completed on May 10, 1869.