Education Week, via a kind reader:

EdWeek Maps is the only place to find comparable, reliable, readily accessible data on graduation rates and other indicators for every school district and high school in the country.
The Editorial Projects in Education Research Center is proud to present this powerful online mapping tool to help the public, policymakers, and educational leaders combat the nation’s graduation crisis. EdWeek Maps is the only place to find comparable, reliable data on graduation rates for every school district and high school in the country.
This Web-based application allows users to easily map out graduation rates by zooming in on any of the nation’s individual school districts. Users can then access detailed information for that district or any of its high schools.