Although charter schools have rapidly proliferated over the past decade, they still serve only a tiny proportion of American students.  The larger immediate impact, then, may be the effects of charters on surrounding schools -- which has studied far less frequently than the effects of charters on their own students.  Charter schools are designed to foster markets wherein other schools compete to offer a higher-quality education, which should work given that parents consistently report that they choose schools based on academic performance.  Studies of parents' actual choices, however, indicate that other factors (e.g. distance, racial make-up, safety, etc.) also play an important role in the decision process.  Which means that there may be less difficult ways to attract students than increasing quality.

We examine the response to charter school competition in NYC by examining school-level demographic data for middle school students from 2003 through 2012, the earliest and latest years publicly available and a time of rapid expansion for charter schools in the city (4 charter middle schools were open in the fall of 2003 compared to 59 in fall 2011).  Two defining characteristics of charter schools in NYC are that they are smaller than traditional public schools, and are named either after the academic theme of the schools (e.g. the Hellenic Classical Charter School) or with an inspirational title (e.g. the Knowledge is Power Program Academy).  Since these are among the most easily observable facets of a school, it would be rational for a district to create new public schools in the same mold if the goal is to compete with charter schools for enrollment.

Indeed, the city seems to have done just this -- closing down myriad large schools and opening new, smaller schools in their stead.  We coded every school that housed more than 10 6th-8th graders in each year between 2003-04 and 2011-12 as traditional public, charter, or charter-like based on size and name.  We find that the number of charter-like schools more than quadrupled, from 52 to 210, during this time.  The result is that the percent of students attending traditional public schools declined from 92% to 70%.  The decline was more marked for poor and minority students than others, though.  75% of White students remain enrolled in traditional public schools, for example, compared to only 57% of Black students.

In short, many more students are attending small, specialized schools that are often de-coupled from surrounding neighborhoods.  We term this trend the "charterization" of schools.

This charterization of schools is yielding a new kind of segregation: white, affluent students attend large, comprehensive, neighborhood schools while poorer and minority students enroll in small, specialized schools often without neighborhood boundaries.  The consequences of this pattern are potentially profound: in 60 years we have shifted from "separate but equal" being deemed "inherently unequal" to intentionally creating separate and unequal systems of schooling.  The long-term question is whether this differentiation will ultimately prove more successful than desegregation efforts at narrowing achievement gaps or reduce social cohesion and widen inequality instead.