 As part of the unification of the three subway companies that comprised the New York City Subway , elevated lines were being shut down all over the city and replaced by subways , continuing the IND 's trend of phasing out elevated lines and streetcars in favor of new subways . For example , the IND Sixth Avenue Line replaced the Sixth Avenue Elevated , while the IND Fulton Street Line replaced the Fulton Street Elevated . Demolition of the <unk> also had the perceived effect of revitalizing the neighborhoods . The northern half of the Second Avenue Elevated , serving the Upper East Side and East Harlem closed in 1940 ; the southern half , running through Lower Manhattan , East Midtown and across the Queensborough Bridge to Queens , closed on June 13 , 1942 . The demolition of the Second Avenue elevated caused overcrowding on the Astoria and Flushing Lines in Queens , which no longer had direct service along Manhattan 's far East Side . Because of the elevated line 's closure , as well as a corresponding increase in the East Side population , the need for a Second Avenue subway increased . 
