From today's NYT, "Large urban-suburban gap seen in graduation rates":
Noteworthy in this article is not only the gap in graduation rates, but also the discussion of how to compute graduation rates. The article points out that graduation rates were for decades overstated in official publications, for ex by counting students receiving GED certificates as graduates or by basing calculations on the percentage of enrolled 12th graders who received a diploma, disregarding students who had dropped out before 12th grade.
PURE Reform encountered this methodology problem when a Right to Know request for graduation rates at city high schools was met with a report showing extremely high graduation rates, in contradiction to statments being made at Pittsburgh Promise presentations about a high dropout rate in Pittsburgh. There does not yet seem to be clear information available on how the graduation rate in Pittsburgh may have changed over the last 3 years or so.