Pittsburgh, like many a post-industrial city, is not exactly awash in cash. But it turns out the city is sitting on a goldmine — a recent audit found that its trees are worth $2.4 million.

Trees are usually thought of as a luxury for a city (you can tell because of how much greener it is in wealthier areas), and luxuries are something Pittsburgh can ill afford. So Pittsburgh, as Nate Seltenrich explains at Next City, decided to actually find out whether its trees were worth the cost of the maintenance they require. In other words, the city decided to measure its trees as it would any asset.

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They didn’t even look at all the trees, just the ones in sidewalks and medians:

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To calculate the value of Pittsburgh’s street trees, a non-profit called Friends of the Pittsburgh Urban Forest (now Tree Pittsburgh) turned to a modeling program called i-Tree, released in 2006 by the U.S. Forest Service in partnership with Davey Tree company. Now in its fifth iteration, the free program allows cities and other users to describe the benefits of trees in language clear enough for those who can’t tell an ash from an aspen.

According to this program, Pittsburgh’s sidewalk and median trees were worth $2.4 million. That’s both a fair bit of money and a whole lot more than the city was spending on keeping them up. Verdict: Even when you’re not getting all mushy-gushy about green space and its value, trees aren’t luxuries. They’re investments that are worth every penny you spend and more.