A study by an Atlanta based group finds that low-income students are now in the majority at Tennessee public schools. The reasons they name: "lower birthrates among higher-income groups, increased immigration, and declines in the number of jobs available to people with less education." The researchers downplay private schools and homeschooling despite rising participation in both.
I would want to see this group's research methods for isolating certain factors and ignoring others before I accept their conclusions. And I want to see who their private donors are (which I could not see from their last audit), in order to determine whether their income flow affected any research bias. Another interesting question is how many on their board or administration have private school ties. Increased immigration and declining jobs seem plausible, but so do private school growth and an expanding lower class beyond birth rate trends.
UPDATE: Facing South views the study results with less concern than I did.