After the IND Sixth Avenue Line was completed in 1940, the city went into great debt, and only 33 new stations have been added to the system since, nineteen of which were part of defunct railways that already existed. Five stations were on the abandoned New York, Westchester and Boston Railway, which was incorporated into the system in 1941 as the IRT Dyre Avenue Line. Fourteen more stations were on the abandoned LIRR Rockaway Beach Branch (now the IND Rockaway Line), which opened in 1955. Two stations (57th Street and Grand Street) were part of the Chrystie Street Connection, and opened in 1968; the Harlem–148th Street terminal opened that same year in an unrelated project. Six were built as part of a 1968 plan: three on the Archer Avenue Lines, opened in 1988, and three on the 63rd Street Lines, opened in 1989. The new South Ferry station was built and connected to the existing Whitehall Street–South Ferry station in 2009. The one-stop 7 Subway Extension to the west side of Manhattan, consisting of the 34th Street–Hudson Yards station, was opened in 2015, and three stations on the Second Avenue Subway in the Upper East Side were opened in the beginning of 2017.