The two-year long research project examined choice programs in Detroit, Milwaukee, St. Louis, San Antonio, and Montgomery County, Maryland; African American and Hispanic families' views of choice plans; voucher initiatives in higher education and preschool settings; and the public and private school markets overseas.
From the summary of the report:
Choice Can Increase Racial Segregation
School choice also has the potential to further the re-segregation of public schools. For example, Montgomery County, Maryland, a suburb of Washington, D.C., created magnet schools as part of its school desegregation efforts in the late 1970s. Researchers found that many parents choose magnet schools on the basis of racial composition and cultural similarity. White parents tend to choose schools with higher white enrollment, while black parents select schools with higher black enrollment. Only by using their authority to deny transfer requests have school officials kept the choice process from increasing segregation.