Develop your own research hypothesis to use in a one-sided two-sample z-test for population proportions. One way to start is to imagine the potential social impacts of a major historical event, such as the Civil War, Industrialization, or the Great Migration. Then, think how such an impact might be reflected in a quantitative form in the Census. What can be measured depends on what questions were asked in Census used at that time. Search on “index of census questions” to find a breakdown of which questions were asked and when.