With more than 250 million cars on American roads, transportation is the biggest single source of greenhouse gas emissions in the United States. 

Now a new map from the New York Times is sharing exactly where all those emissions are coming from, and it turns out it’s largely regular Americans driving around in their cars. The Times and researchers from Boston University created what they call “The Most Detailed Map of Auto Emissions in America,” showing how every major metropolitan area contributes to greenhouse gases through transportation.

Nadja Popovich, graphics editor for the Times’ climate team, spoke with “Marketplace” host Molly Wood about the reporting and how the economy has helped fuel the rise in auto emissions.

Click the audio player above to hear the interview.