 Construction on the Second Avenue line started in 1972 , but was halted in 1975 because of the city 's major fiscal crisis ; only a few small segments of the line were completed at the time . Simultaneously , construction work on the 63rd Street Lines , which would connect the Second Avenue Line and the IND Queens Boulevard Line to the BMT Broadway Line and the IND Sixth Avenue Line , started in 1969 . Work on the 63rd Street line continued even after construction on the Second Avenue line ended . The first segment of the 63rd Street Lines — which opened in October 1989 and extended to 21st Street – Queensbridge in Long Island City , Queens — left provisions for future construction to the Second Avenue Line . 
