From the National Center for Educational Statistics. CCD is a comprehensive, annual, national statistical database of information concerning all public elementary and secondary schools (approximately 95,000) and school districts (approximately 17,000).
Operated by the NCES with the aim to help, "you understand the social and spatial context of education" [from source]. Includes data on K-12, Higher-education, school districts, locale boundaries, and social/economic factors.
Searchable database, available in for English and Spanish, for locating school report cards. District and State Report Cards are only available from 2002 forward. Spanish versions of report cards are only available from 2001 forward.