 Further revision of the plan and more studies followed . By 1939 , construction had been postponed indefinitely , and Second Avenue line was relegated to " proposed " status , and was number 14 on the Board of Transportation 's list of important transportation projects . The Second Avenue line was also cut to two tracks , but now had a connection to the BMT Broadway Line . The reduced plan now had a single northern branch through Throggs Neck , Bronx , and a branch south into Brooklyn , connecting to a stub of the IND Fulton Street Line at the Court Street station , which is now the site of the New York Transit Museum . The subway was now also US $ 249 million ( equivalent to $ 4 @,@ 006 @,@ 000 @,@ 000 in 2015 ) . The United States ' entry into World War II in 1941 halted all but the most urgent public works projects , delaying the Second Avenue Line once again . 
