The difference in stature between white women and black women has now stretched to three-quarters of an inch and appears to be increasing, the study using Centers for Disease Control and Prevention data found.
The main culprit appears to be diet, The Atlanta Journal-Constitution reported.
The average height of a black woman born in the 1980s is just under 5 feet 4 inches. Her mother, born in the 1960s, is more than half an inch taller. Her grandmother, born in the 1940s, is a bit taller still.
The average white woman born in the 1980s is about a half-inch taller than her mother.
The gap is "truly phenomenal," economist and height historian John Komlos, who conducted the analysis, told the newspaper.
He said he sees significance in this because "height is a very good overall indicator of how well the human organism thrives in its socioeconomic environment."
He also observed that while the heights of low- and middle-income black women are decreasing, upper-income black women are growing taller and closing the gap with their white counterparts.
"The only reasonable explanation we can come up with is diet and the obesity epidemic among (middle- and low-income) black women," Komlos said.