The reality, though, is more complicated. Consider one illustration: For the last few years, Philadelphia has converted a handful of parking spots in front of neighborhood businesses into temporary "parklets" no bigger than the space that might fit one or two cars (these tiny interventions are now popular in a lot of cities). Records from adjacent businesses show sales went up about 20 percent immediately after the parks were installed, relative to right beforehand.
That data comes from a recent study by the University City District, a neighborhood development organization in Philadelphia that sent interns out in the spring and summer of 2013 to exhaustively record what happened after a half-dozen of these tiny parks were placed. Most of them included tables, planters and bike racks that created something in between a new public park and an outdoor extension to nearby cafes and sandwich shops.
The result: a lot more people packed into these spaces than could ever be accommodated by a single car.
Outside the taco shop, as many as 150 people used a space over the course of the day that was only about 240 square feet in size. The seats were packed outside the café in early afternoon, and an ice cream shop in the evening:
Not all of these people were spending money at these nearby businesses (that's a good sign — it means that people recognized they could treat these spaces as public parks and not private outdoor restaurants). But the sales data shared by these businesses suggests that the extra foot traffic — and the outdoor attraction — was a boon for business, even when it came at the expense of a little parking.
The takeaway here isn't that we should turn parking spaces everywhere into public parks. This idea wouldn't work in a lot of other contexts (you're a lot more likely to need your car on the way out of an Ikea than a coffee shop, for one thing). But it illustrates that a parking spot isn't always the best use of roadside real estate, although we often treat it as such. And it adds a little more evidence to the growing economic case for deploying our streets differently, for use by more than cars. Other research suggests that cyclists may actually spend more than drivers at some kinds of businesses because it's easier for them to pop in often and unplanned. And there are some signs that bikeshare docks boost business nearby, too.