The figure comes from measurements, not responses. According to the official anthropometric reference data report published by the Centers for Disease Control and Prevention, in the NHANES cycle collected between August 2021 and August 2023, women aged 20 and older in the United States averaged 63,5 inches in height (about 1,61 meters, or 5 feet and 3,5 inches) and weighed 171,8 pounds (about 78 kilograms).
It is a population average, not a measure that describes every woman.
The mid-to-late 2010s cycles recorded somewhat lower average weights, around 170 to 171 pounds: the most recent figure is just above that range.
