From 1954 to 2008 African-American 17-year-olds consistently scored at the level of white 14-year-olds on tests of mathematics and reading

A 3+ year gap between blacks and whites at age 17 is equal to an IQ for African-American 17-year-olds of about 85, the same as that found using standardized IQ tests. Black 17-year-olds have not closed the combined mathematics and reading gap on Hispanic 17-year-olds (for many of whom English is a second language), and barely closed it on white 13-year-olds. Black 17-year-olds lag white 17-year olds by over three years. Black achievement scores average 1.6 years behind those of whites in grade 6 (at age 12); 2.4 years in grade 9 (age 15); and 3.3 years in grade 12 (age 18). Black scores even average below those of American Indians, despite that group scoring lower on most socioeconomic indicators. Some researchers believe that the mean African-American IQ might actually be only 78 rather than 85 - in part because, even today, test developers and educational researchers seldom get to examine the very lowest scoring segments of the black population in inner cities.