The BRFSS is used to track state-level trends in weight and obesity, healthy eating, and physical activity. But the BRFSS also asks its respondents, all of whom are age 18 and older, about their height. That allows us to map out differences in average adult height at the state level.
Here, for instance, is a map of average male height. At the state level it runs from about 175 centimeters (5′9″) in Hawaii to about 180 centimeters, or 5′11″, in Alabama and Iowa. Generally speaking, men in the northern plains states and a swath of Appalachia report the tallest heights, while men in the northeast and southwest tend to be shorter.
What’s driving those differences? Race is one big factor. Medical examination data maintained by the CDC shows that white (average height of 5′10″ rounded to the nearest inch) and black (5′9″) men tend to be significantly taller than Asian (5′7″) or Hispanic (5′7″) men. Hawaii, California and New York have high Hispanic and Asian populations. In Hawaii, fewer than one third of the population identifies as black or white. In Alabama, by contrast, 96 percent of the population is black or white.
Those racial differences underscore a key point about height: much of the differences in height within a population are a function of genetics. But not all of them. A simple way to control for the effects of race is to map the data for one racial subset of men. We’ll use white men in this case, for the sole reason that that gives us the biggest sample size nationwide, and hence the most reliable data.
Even when you isolate white men, the map follows the same general contours: the tallest men live in the plains and Alabama, while the shortest are found in the northeast and southwest. This suggests there are some other factors at play in determining height. Researchers believe childhood nutrition is a big one.
The nationwide picture for women looks a little different.
First, women are shorter overall, with a nationwide average of about 163 centimeters, or 5′4″. Geographically speaking, the tall women are clustered more tightly in the northern plains than the men are. The tallest women, with an average height of about 5′5″, are in South Dakota. The shortest, again, are in Hawaii, with an average height a hair less than 5′3″.
In the interest of completeness we’ll do the same exercise for white women that we did for white men, to isolate the effects of race.
No real surprises there.
Now, sharp-eyed readers may have already noticed that there’s one more potentially big source error lurking behind these numbers: they’re self-reported. A phone interviewer asked people how tall they were and recorded their answers.
Here’s the thing: people lie about their height. Men lie about it more than women. There are any number of academic papers illustrating the phenomenon, but it’s easy enough to do this ourselves. Every year the CDC administers a separate, smaller survey, called the National Health and Nutrition Examination Survey (NHANES), which includes a medical exam administered by a professional. The examiners collect standard body measurements from the survey participants, like weight, height and blood pressure.
For our national samples in a given year, we can compare the BRFSS’s self-reported heights with the actual measurements taken by medical professionals for the NHANES. In 2016, the most recent year for which this direct comparison is possible, men self-reported their heights an average of 2.3 centimeters, or nearly a full inch, above what their actual measurements showed. Women over-reported their height too, by about 1.5 centimeters. So keep that in mind when looking at the maps above. Unfortunately, the NHANES doesn’t release state-level data so we have no way of knowing which states lie the most about their heights.
Height tends not to get discussed as much as say, weight, in public health conversations. Height is a useful biometric marker in its own way, especially at the population level. “Human growth can be limited by poor childhood nutrition and illness,” as Oxford economist Max Roser explains. “This makes height strongly correlated with living standards and hence a good proxy for them.”