>>1472333>>1472344There is definitely demand for traveling between the outer boroughs, it's just that the system was envisioned as Manhattan-centric by the IRT, BMT and IND so new expansions just end up on focusing on Manhattan (or outer borough extensions of lines from Manhattan) and we barely expand nowadays. It's worth noting that the Triboro RX proposal basically would be a line connecting the outer boroughs using several railroad rights-of-way (although if it were ever built, it probably wouldn't go to the Bronx due to the Hell Gate Bridge between Queens and the Bronx already being used by Amtrak, freight rail, and Metro-North in the future).