WALKING isn’t just good for you. It has become an indicator of your socioeconomic status.

Until the 1990s, exclusive suburban homes that were accessible only by car cost more, per square foot, than other kinds of American housing. Now, however, these suburbs have become overbuilt, and housing values have fallen. Today, the most valuable real estate lies in walkable urban locations. Many of these now pricey places were slums just 30 years ago.

Mariela Alfonzo and I just released a Brookings Institution study that measures values of commercial and residential real estate in the Washington, D.C., metropolitan area, which includes the surrounding suburbs in Virginia and Maryland. Our research shows that real estate values increase as neighborhoods became more walkable, where everyday needs, including working, can be met by walking, transit or biking. There is a five-step “ladder” of walkability, from least to most walkable. On average, each step up the walkability ladder adds $9 per square foot to annual office rents, $7 per square foot to retail rents, more than $300 per month to apartment rents and nearly $82 per square foot to home values.

As a neighborhood moves up each step of the five-step walkability ladder, the average household income of those who live there increases some $10,000. People who live in more walkable places tend to earn more, but they also tend to pay a higher percentage of their income for housing.

Although we have not studied all urban areas to the same degree, these findings appear to apply to much of the rest of the country. In metropolitan Seattle in 1996, the suburban Redmond area, home to Microsoft, had the same price per square foot as Capitol Hill, a walkable area adjacent to downtown, based on data from Zillow. Today, Capitol Hill is valued nearly 50 percent above Redmond.