The Steinway Tunnel is a pair of tubes carrying the IRT Flushing Line of the New York City Subway under the East River between 42nd Street in Manhattan and 51st Avenue in Long Island City, Queens, in New York City. It was originally designed and built as an interurban trolley tunnel, with stations near the current Hunters Point Avenue and Grand Central stations.

The IRT Flushing Line is a rapid transit route of the New York City Subway system, named for its eastern terminal in Flushing, Queens. It is operated as part of the A Division. The Interborough Rapid Transit Company (IRT), a private operator, had constructed the section of the line from Flushing, Queens, to Times Square, Manhattan between 1915 and 1928. A western extension was opened to Hudson Yards in western Manhattan in 2015, and the line now stretches from Flushing to Chelsea, Manhattan. It carries trains of the 7 local service, as well as the express <7> during rush hours in the peak direction. It is the only currently operational IRT line to serve Queens.