SOURCE: U.S. Department of Education, Institute of Education Sciences, National Center for Education Statistics, National Assessment of Educational Progress (NAEP), 2003, 2005, and 2007 Mathematics Assessments.
NAEP started collecting data by U.S. census regions in 2003. See more information on which states are included in each region.
To read more about achievement levels and how they are set, see Reporting the Assessment—Scale Scores and Achievement Levels.