A new study conducted on behalf of a Bay State congressman shows the cost of building a North South Rail Link between North and South Stations is less than one third the estimated economic benefit such a project would bring.

The study, conducted by the Harvard Kennedy School at the request of U.S. Rep. Seth Moulton and released Monday, shows that linking the region’s currently unconnected rail networks would result in “an estimated $30 billion in benefits for the Commonwealth.”

“The Rail Link is the single most important project for transportation in Massachusetts. It makes regional rail not just possible but successful. It does more to boost housing than any housing bill. And it has huge benefits for climate and racial justice in historically forgotten communities. Until we build the Rail Link, we won’t just be stuck in traffic, we’ll be stuck in the past,” Moulton said with the release of the report.

The idea of linking North Station and the commuter and regional rail lines that run to it with the national train service brought to South Station is not new, but this study is the first that examined both the cost of a building a pair of about 3-mile-long rail tunnels under Boston and the probable economic benefits, according to Moulton’s staff.

At an estimated cost of just under $8 billion, it’s a steal when compared to the benefit it would bring — not just to Boston — but the entire rail-served region, according to the Salem congressman. Linking the lines, according to the research, “quadruples commuter rail ridership” and “incentivizes over 150,000 new housing units.”

“The question is no longer ‘Can we afford to build the link?’ but ‘Can we afford not to?’” Moulton said.

Even if Moulton’s construction cost numbers are off — a MassDOT study conducted in 2018 which examined several options for a North South Rail Link found the cost of the project could range from $12 billion to $28 billion — the proposed project could be a “real win-win for everyone” and solve other problems, like the state’s chronic road congestion, according to Linda Blimes, the Daniel Patrick Moynihan Chair in Public Policy and Public Finance at the Harvard Kennedy School.

“The North-South Rail Link is an investment that will repay huge dividends for the Commonwealth, and for the entire New England Region. Connecting North and South stations will eliminate a transportation bottleneck that has caused congestion for decades and make it possible for the rail system to expand economic opportunities,” she said.