|Figure 3.||Percentage of persons 25 years old and over, by highest level of educational attainment: Selected years, 1940 through 2011|
1 Includes high school completion through equivalency programs, such as a GED program. For years prior to 1993, includes all persons with 4 or more years of high school.
2 For years prior to 1993, includes all persons with 4 or more years of college.
SOURCE: U.S. Department of Commerce, Census Bureau, U.S. Census of Population: 1960, Vol. I, Part 1; J.K. Folger and C.B. Nam, Education of the American Population (1960 Census Monograph); Current Population Reports, Series P-20, various years; and Current Population Survey (CPS), March 1961 through March 2011.