Gale Virtual Reference Library in Holman Library contains the Information Plus Reference Series. Focused primarily, though not entirely, on domestic social issues, each report is chock full of statistical data.
Fig. 6. "census tabulator." Online Photograph. Encyclopædia Britannica Online. April 2012.
Most statistics in our country come from data gathered by the United States government.
Many of the city-related statistics you will come across are generated by the Census. The complete Census is conducted every 10 years by the U.S. Census Bureau, and during the census, government workers walk around neighborhoods gathering data about household demographics like race, income, education level, and much more. Some census data is updated more frequently.
For links to many more statistical resources, check out this library research guide.
You can also ask a librarian for help.