The Denver, South Park and Pacific Railroad is a private, adult large scale outdoor railroad, comprised of people interested
in all aspects of railroading, but especially in building and operating large scale model steam locomotives (including electric and internal combustion powered
equipment). The track guage is 7 5/8" laid at ground level.
The large scale outdoor railroad hobby originally started in England in the 1920's and over the years it spread to Europe, the U.S., Canada, Australia, New Zealand, South Africa, and Japan. All over the world, there are hundreds of clubs and associations as well as many thousands of private backyard railroads. The world's largest live steam railroad with over 30 actual miles of 7 1/2 inch trackage is Train Mountain Railroad in Chiloquin, Oregon. Other notable railroads are the Maricopa (Phoenix) Live Steamers and Riverside Live Steamers located in Riverside, CA.
The Discover Live Steam website contains a listing of many of the live steam railroads worldwide -> Discover Live Steam It also contains a large FOR SALE listing of locomotives, rolling stock and accessories relative to the hobby.
Originally the hobby was comprised of folks who built actual large scale live steam railroad locomotives. Since then, the hobby has grown with other scale model locomotives whose prototypes are diesel (gasoline) and electric (battery). One of the most famous live steam railroads was Walt Disney's Carolwood Pacific Railroad built around his home in the hills above Los Angeles. It later inspired Mr. Disney to surround his planned Disneyland amusement parks with working, narrow gauge railroads. Here is the link to his live steam railroad: Disney Track
Here is the link to a U-TUBE video of his live steam railroad: Disney Railroad