The Infrastructurist reports on a new academic study that considers the full environmental impact of parking. But in order to provide an answer to this query, the researchers had to first consider another question: just how many parking spots are there in the United States?

Turns out that’s no easy task; in fact, according to the authors, no such “nationwide inventory” has ever been done. “It’s kind of like dark matter in the universe,” Donald Shoup, the so-called “prophet of parking” (and not part of the study), told Inside Science. “We know it’s there, but we don’t have any idea how much there is.” When the Berkeley researchers crunched the numbers, they came up with five scenarios of available U.S. parking that ranged from 105 million spots to 2 billion. Give or take, I guess.

The most likely estimate points to roughly 800 million spaces across the country, and the construction and maintenance of those spaces do, in fact, take a large cumulative toll on the environment. When parking spots are taken into account, an average car’s per-mile carbon emissions go up as much as 10 percent, the authors conclude. They also report that, over the course of a car’s lifetime, emissions of sulfur dioxide and soot rise 24 percent and 89 percent, respectively, once parking is properly considered.

Those are just part of a broad “suite of impacts” that includes previously studied costs like the “heat island effect” — the term for when dark pavement raises the temperature of a city, leading to additional energy demands for cooling. And atmospheric costs are only part of the suite. According to the paper’s lead author, Mikhail Chester, there may be a larger infrastructure for parking than for roadways. If that’s the case, there would seem to be another great cost to all this parking: the relative cost of useful space.

I like the comments from “the prophet of parking.” While there are not probably too many people in the world who would want to know the exact figure of parking spots in the United States, it is important to know this fact in order to understand the larger impact of parking.

Parking itself is an interesting phenomenon. In a culture that loves automobiles, parking spots are essential features are many places. There is much evidence that if Americans can’t find a relatively cheap parking spot, they are likely to go elsewhere. Some of the allure of the shopping mall, with the first ones constructed in the mid 1900s, was that the consumer had a vast area of free parking as opposed to the crowded streets of downtowns. Homes have to have their own form of parking spaces, to the point of many homes from recent decades leading with their garages (and earning the nickname “snout houses” for how this garage protrudes toward the street).

But of course, as this study points out, parking spots come at a cost.

A related question that I would be interested in knowing the answer to: how many parking spots are occupied at different times of the day? How many parking spots in America are constructed for the 8-5 work hours and then sit empty the rest of the day?