“There is a lot of controversy around the country,” says Rick Gustafson, former executive director of the Portland system and a consultant to several cities planning streetcar systems. “At the same time, you’ve got 20 systems funded. So some cities are able to put it together, hold it together, build it. Others are facing all kinds of battles and fights.”

Stable political leadership is vital, Mr. Gustafson said. “There’s benefit in keeping all the initial investors and interested parties,” he said. Otherwise, the projects may not “survive the political transitions that occur in elected office.”

The Arlington reversal was a surprise. The 26-square-mile county is widely regarded as progressive on matters of transit and urban planning — it already has five Metro subway stations in a two-mile stretch on its north side — and the decision to drop the streetcars was made shortly after the suburban county had awarded a $26 million preliminary engineering contract.

The 7.5-mile Columbia Pike line was considered such a sure thing that developers had already started investing along the route and citing the streetcar in their plans. Under the adopted timetable, the south-county line was scheduled to open in 2020.

But John Vihstadt, a streetcar critic and a subway commuter to his Washington law office, had just been elected to the Arlington County board. The campaign’s dominant issue was the planned system, with Mr. Vihstadt arguing that it would be too expensive and ineffective, compared with faster bus service. The vote was seen as a referendum on the project that had been planned since the 1990s and formally approved in 2006.

“At the end of the day,” Mr. Vihstadt said, “Arlington voters concluded the streetcar didn’t make sense from a transit or economic perspective, that it would cost too much and do too little. I was the vehicle for that sentiment.”