The 42nd Street Shuttle is a line and service of the IRT division of the New York City Subway. It is sometimes referred to as the Grand Central/Times Square Shuttle, since these are the only stations served by the shuttle. It runs at all times but late nights, connecting Times Square to Grand Central Station under 42nd Street. Instead, for late nights the 3 is used. It is the shortest regular service in the system, running 0.8 mile (1.3 km) in officially one minute. In order to distingush it from the other shuttles in the system, NYCT Rapid Transit Operations refers to it as the "0".