Boston already has what many large cities have spent millions of dollars trying to create: a streetcar serving an otherwise transit-starved area. So there’s considerable irony that just as Washington, D.C., prepares its long-awaited streetcar for opening, and as New York City mayor Bill de Blasio proposes a new 16-mile streetcar line in Brooklyn and Queens, MBTA administrators and the T fiscal control board has raised the possibility of eliminating the Mattapan trolley. It’s not a decision that the board should make without a full consideration of the long-term lost opportunities.

The control board, charged with whipping the T’s finances into shape, put the 2.5-mile Ashmont-to-Mattapan line on the chopping block because maintaining its fleet of ancient trolleys likely costs more than replacement buses would. It’s an attractive target: T workers have to make some parts for the World War II-era trolleys by hand at their Everett shops. Only about 5,000 riders use the trolleys every day, less than the ridership on some bus lines. The control board’s job is to ask tough questions, and whether the Mattapan line has a future is certainly a conversation that needs to happen.

“There’s vehicles running on the Mattapan line that were procured in 1946,’’ said Steve Poftak, one of the control board members. “The notion of running them for another 15-30 years is not practical. I’m concerned that they are very expensive to run, and the MBTA needs to take a look at all its operations and figure out how it can operate sustainably and reliably. There’s a limit to the amount of subsidy we can put in.’’

The T could clearly save money by ditching the trolleys, paving over the tracks, and running buses along the right-of-way instead (exactly how much money is one of the questions the control board will need to answer before making any decisions). But that may well be a short-sighted way to frame the question. Board members should give some thought to why New York, Salt Lake City, Washington, Portland, Tucson, and other US cities have commited to streetcar lines, despite what sometimes seem like unfavorable economics. What those cities have concluded is that streetcars make communities more attractive and liveable in ways that buses don’t. One need only walk down the H Street corridor in Northeast Washington, where the streetcar is due to start running on Saturday, to see how much the neighborhood has already changed.

Those new streetcar lines generally went hand-in-hand with rezoning efforts, which contributed to their success. That’s a process that’s never really been launched around the Mattapan line stations in Boston, because the line was already there. But it’s an idea worth exploring. Tim McCarthy, the city councilor who represents Mattapan Square and supports the trolley, touted the area as a possible anchor for transit-oriented development. Those development opportunities would be lost if the trolley goes.

The profits from more development wouldn’t accrue to the T’s bottom line, and a hard-nosed board might decide to ax the trolley anyway. That just underscores the need to link transit funding to development. Measures under consideration on Beacon Hill would provide a way for the T to realize some upside when its services create growth. But at least in the case of the Mattapan line, the T will feel the economic ripple effects anyway. The agency is currently trying to sell its real estate next to the Mattapan station. It’s hard to see how taking away the neighborhood’s signature transit amenity would make the T’s 2.5-acre parcel more valuable. If anything, by ending the trolley, the T could be shooting itself in the foot.

Given the age of the equipment, it was only a matter of time before the T called the question of the Mattapan line’s future. The board is only doing its job by considering its options. Now that that discussion is here, though, the goal should be to get the most out of a unique asset that the region would miss if it were gone. “Once you pull up those tracks, you’re going to regret it,’’ says McCarthy. Indeed, the T and the city should be recommitting to the Mattapan line, not allowing it to fade away.