Escalators are moving staircases that transport people between floors using a motor-driven chain of connected steps. Nathan Ames invented the first escalator in the 1860s, but was unable to build it. Reno and Otis emerged as the leading developers of escalators in the early 1900s, with Otis installing the first practical escalators in New York City and Paris. Otis went on to become the sole manufacturer of escalators, installing hundreds between 1900-1920 primarily in stores and transportation hubs. Modern escalators consist of steps, tracks, trusses and handrails to safely move people in an endless loop. Future escalators may be spiral to reduce space usage.