"The WorldPop project aims to meet these needs through the provision of detailed and open access population distribution datasets built using transparent approaches." Examples of different kinds of population graphics. Probably not actually useful for this, though.
Includes datasets on Population Policies, Trends in Migration, Marriage, Fertility, and Contraception as well as urbanization.
Important! The Population Policies dataset is available in a better, interactive format. Be sure to look at the links in the sidebar, especially the Helpful Links link!
Gives a good overview of statistical information for states, counties, and cities. Links to additional (more detailed) data from sources such as American FactFinder, the American Community Survey, population projections, etc. Probably all you will need for this assignment.