The second avenue subway extension costs $2.1 billion dollars per mile to build.[1] [1] https://www.thoughtco.com/rail-transit-projects-costs-2798796 https://w

The second avenue subway extension costs $2.1 billion dollars per mile to build.[1] [1] https://www.thoughtco.com/rail-transit-projects-costs-2798796 https://www.thoughtco.com/rail-transit-projects-costs-279879...