he u.s. census bureau collects information on the racial composition of people in counties throughout the u.s. by asking survey respondents to identify their race. this information allows researchers to estimate the percentage of people in a county who are in various racial categories. the histogram below displays the percentage of adults who identified their race as white in 1,000 counties in the u.s. in 2010. the number above each bar is the frequency of the group of values. the midpoint of each bar is the position on the horizontal axis at the center of the bar.