1. Explain why these graphs are histograms by describing the variable on the y axis, units used, what the markings are for, and what is being measured on the x axis. Note that these density population graphs are standing on end, and each one is two graphs side by side (one for males and one for females) sharing the same x axis.

2. Describe the shape, center, and spread of the U.S. population's age in 1970 and then in 2020.

3. What story does each graph tell you about age distribution in 1970 and 2020?

4. What social, medical, and public health changes have occurred in the last 50 years to explain the difference in the age distribution of the United States?

United States of America: Population in 1970 Males Females A histogram graph showing the population in millions by gender and age in the United States in 1970. Medium-variant data is shown as colored bars, and uncertainty is shown in gray for 95 per cent prediction intervals. Age in 1970 Male Female Population Population in in Millions Millions 95-100