The latest research suggests that the high school graduation rate, properly measured, is perhaps 5 percentage points higher than it was a half century ago, compared to a rise of more than 70 percentage points in the previous half century.20 So although educational attainment as measured by high school graduation has risen over more than 125 years, that inexplicable and prolonged halt after the mid-1960s will merit revisiting later in this book, because it turns out that many other measures of social progress halted at the very same time.
