It’s a truism in politics that if you repeat a statement often enough, people will believe it, regardless of whether it’s true. In Arlington, a cohort of commentators and activists has been chanting that the County Board is full of profligate spenders. Now that claim has started to have currency in county politics , even though it’s grounded in little at all.

Fifty years ago, Arlington was an aging suburb that progress had passed by on the way to greener pastures in Fairfax County. Outdated retail strips, struggling businesses and a declining population portended a bleak future. State and federal planners saw Arlington mostly as space to be traversed between home and work, and they proposed cutting up its neighborhoods for commuter roads.

County residents and leaders did not respond to this challenge by spending as little as possible in the vain hope that doing so would attract people and economic growth. Instead, they campaigned to build an expensive Metrorail subway and put it under Wilson Boulevard, with the goal of transforming it from a tired suburban strip into a new downtown. They planned walkable centers with more housing, jobs and retail, plus new streets and sidewalks, while protecting the character of older neighborhoods.

It paid off. Now Arlington is a desirable place to live. It also saved money. Half of the county’s property tax assessment value comes from only 11 percent of its land, along the Metro corridors. As a result, Arlington typically enjoys the lowest property tax rate in Northern Virginia.

Still, as real estate booms, house prices rise and assessments go up. This year, Arlington cut its residential tax rate by a penny per $100 of value, but rising assessments meant that most people paid more. It’s not unfair for residents to dislike this or to demand a more thorough discussion of overall spending priorities. But it would be a big mistake to simply point at anything new and declare it wasteful.

The Columbia Pike streetcar is a great example. County leaders believe it will bring many of the benefits that Metro brought to places such as Clarendon. According to a projection released this week, 37,100 people will ride daily on the combined Columbia Pike and Crystal City lines. That’s more people than now ride the MARC system (34,100), Baltimore light rail (26,800) or the whole Fairfax Connector bus system (36,300).

The Columbia Pike line is estimated to cost $358 million, including a 20 percent contingency; the Crystal City segment will bring the total to $585 million, including the contingency. By comparison, the District is spending $663 million to replace the Frederick Douglass Bridge, which carries 77,000 vehicles per day; that’s more than the streetcar’s cost just to replace one short piece of the road system. Phase 1 of the Silver Line has cost more than eight times as much as the Columbia Pike streetcar to move just 2.3 times as many people – and that very worthwhile investment is setting up parts of Fairfax and Loudoun counties for the future.

In comparison with other projects, a streetcar on Columbia Pike is a thrifty proposition. But that hadn’t stopped it from being a political punching bag for some who simply attack the price tag without context. News coverage that reports only the cost without discussing benefits does not help, either.

Streetcar opponents constantly hold up phantom alternative bus proposals with less capacity to move peopleand bring far fewer benefits, though indeed for lower cost. They point to high-quality bus rapid transit projects in other cities while opposing the price tag of every element, such as larger and fancier stations, that made those cities’ lines more than just ordinary bus routes. They seem to say Arlington’s only goal should be to spend as little as possible. Instead, the right goal is to make all parts of the county great places to live, in a cost-effective way.

Sadly, this chorus of negativity sounds a lot like, “I’ve got mine, so I don’t want to chip in for anybody else.” That attitude didn’t prevail in 1971, when there was talk about deleting the Virginia Square station during planning for Metrorail, or when the Orange Line could have gone in the median of Interstate 66 for much less expense than under Wilson Boulevard. They didn’t act this way when Clarendon, Ballston and Pentagon City needed new infrastructure to accommodate growth.

Arlington’s success today builds on yesterday’s investments. The next generation needs a similar investment, and now is the time. The county’s current plans, including the streetcar, will position it to succeed in the decades to come as Metrorail has helped it succeed today — as long as residents see through divisive and miserly rhetoric and are willing to get excited about the future.

The writer is editor of the blog Greater Greater Washington.