The Orange Belt Railway was a 3 ft narrow gauge railroad established in 1885 by Russian exile Peter Demens in Florida. It was one of the longest narrow gauge railroads in the United States at the time of its completion in 1888, with a mainline 152 miles (245 km) in length between Sanford and St. Petersburg. It carried citrus, vegetables, and passengers; and it interchanged with two standard gauge lines: the Jacksonville, Tampa and Key West Railway at Lake Monroe, and the Florida Central and Peninsular Railroad at Lacoochee.

Peter Demens, born Pyotr Alexeyevitch Dementyev, was a Russian nobleman who migrated in 1881 to the United States and became a railway owner and one of the founders of St. Petersburg, Florida, United States.