“Over the past decade, Chicago has opened dozens of new high schools, and will open more this fall. The school district is trying to expand the number of “quality school options” and offer students a choice of where to go to school. And in many ways, Chicago high schools seem to be improving. Graduation rates are inching up. The city now boasts five of the top ten high schools in the state.

But a new WBEZ analysis shows an unintended consequence of the choice system: students of different ability levels are being sorted into separate high schools.

Think of it as academic tracking—not within schools, but between them.

The findings raise some of the same long-running questions educators have debated about the academic and social implications of in-school tracking. But they also raise questions about whether the city’s school choice system is actually creating better schools, or whether it’s simply sorting certain students out and leaving the weakest learners in separate, struggling schools.

New York City and New Orleans see a similar dynamic

Despite most New Orleans schools being open to students of all academic levels, “high performing students tend to go to high-performing schools, and low-performing students tend to go to low-performing schools,” says Andrew McEachin, a North Carolina State University professor who has studied school choice in the now all-charter city. “So even though it’s a choice-based district, you see that there’s kind of like a tiered system, where people are choosing schools similar to their background and achievement levels.”

The same thing is happening in New York City. Why? Researchers say “achievement” may be an indication of the resources students have at home. Higher performing students’ families are better at getting information about school quality, navigating the system, and securing things like transportation to school or test prep for entrance exams.”