As part of the unification of the three subway companies that comprised the New York City Subway in 1940, elevated lines were being shut down all over the city and replaced by subways. The northern half of the Second Avenue Elevated, serving the Upper East Side and East Harlem, closed on June 11, 1940; the southern half, running through Lower Manhattan, East Midtown and across the Queensboro 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 to Manhattan's far East Side. The elevated line's closure, as well as a corresponding increase in the East Side's population, increased the need for a Second Avenue subway.