About one in every three users of mass transit in the United States and two-thirds of the nation's rail riders live in New York City and its suburbs. And the cost to maintain one of the world’s most extensive mass transit systems is expensive. Each new subway car, for example, costs $1.4 million. Replacing and maintaining tracks runs the state's Metropolitan Transportation Authority (MTA) about $303 million a year.In order to pay for subway maintenance and projects over the years, the MTA has had to borrow a lot of money for funding. So much so that the MTA is now the fifth biggest debtor in the United States – after the state of California, the state of Massachusetts, New York State, and New York City.Blueprint America looks at the costs of maintaining New York City's transportation system and the difficulties involved when making improvements.