A couple years ago, some of my colleagues at USC set out to answer an old question with a new twist. They wanted to know how many jobs you could find if you lived in a low-income neighborhood. Specifically, they wanted to know how many jobs you could commute to.

Most Americans take it for granted that employment is place-based. You can’t work at a building that’s too far away. But what happens when you can only afford to live in a few of neighborhoods in a city, a reality that many low-income families face? How many jobs are too far away?