These days, Americans seem divided by almost everything. But you know what has proved successful at bringing Americans of different backgrounds together? Unlimited soup, salad, and breadsticks. Also, riblets, onion rings, chicken crispers, and other crowd-pleasers from affordable chain restaurants such as Olive Garden and Applebee’s.

Though sometimes banned by municipalities wanting to "preserve neighborhood character” or slow gentrification, these chains actually provide a hidden social service: They promote much more socioeconomic integration than do independently owned commercial businesses—or, for that matter, traditional public institutions.

That’s according to a provocative new paper from Maxim Massenkoff and Nathan Wilmers. The authors analyzed a massive trove of geolocation data to assess where Americans come into contact with people of different income classes than themselves—if they do at all.

Sadly, the paper also found that many public institutions we might associate with facilitating encounters across class lines instead reinforce seclusion. Parks, schools, libraries, and churches. There are exceptions, but on average, each of these establishments leads to less socioeconomic mixing, more within-income-group hobnobbing, and even more class isolation.