The IRT Third Avenue Line, commonly known as the Third Avenue Elevated, Third Avenue El, or Bronx El, was an elevated railway in Manhattan and the Bronx, New York City. Originally operated by the New York Elevated Railway, an independent railway company, it was acquired by the Interborough Rapid Transit Company (IRT) and eventually became part of the New York City Subway system.

The first segment of the line, with service at most stations, opened from South Ferry to Grand Central Depot on August 26, 1878.[1] Service was extended to Harlem in Manhattan on December 30. In 1881 this line already began the 24/7 service. Service in Manhattan was phased out in the early 1950s and closed completely on May 12, 1955.