Debates about the national high school graduation rate have heated up as various national high school graduation estimates based on the Common Core of Data (CCD) and the Current Population Survey (CPS) do not coincide with one another partially due to different assumptions about graduation age. This study found that (a) while graduation rate by age 18 declined, the rate by age 24 remained relatively constant, creating larger differences between the CCD- and CPS-based rates and that (b) males and minorities particularly take more time to obtain a high school degree among the recent birth cohorts.