The A and AA were the first services on the IND Eighth Avenue Line when it opened on September 10, 1932. The Independent Subway System (IND) used single letters to refer to express services and double letters for local services. The A ran express between 207th Street and Chambers Street/World Trade Center, and the AA ran local between 168th Street and Chambers St/World Trade Center, known at the time as Hudson Terminal. During late-night hours (from 1:45 a.m. to 5:45 a.m.) and on Sundays, the A did not run and the AA made all stops along the line.