^aIn 2006, all states with statewide requirements required ≥2 years of mathematics courses, and only one state required 1 year of science.

NOTES: Data included for all states for 2006 and for all states plus District of Columbia for years before 2006, with two exceptions: in 1987, Arkansas and Vermont required total of 5 mathematics and science credits (2 or 3 credits in each) so not assigned to a category; in 1996, Vermont alone not counted for this reason. Some states had separate requirements for different kinds of diplomas. For these, states categorized by requirements for "standard" diploma or for type most students likely receive, if more than one type and none called standard. In some states and some years, a new requirement enacted by year in column head but did not necessarily apply to graduating class of that year.

SOURCES: Council of Chief State School Officers, Key State Education Policies on PK-12 Education: 2006 (2007); and National Center for Education Statistics, Digest of Education Statistics, 1988 and 1998 editions (1988 and 1999).

Science and Engineering Indicators 2008