Census data can be hard to wade through. Feel free to contact us at firstname.lastname@example.org for a consultation!
There are a number of ways that you can access census data at the University of Michigan.
American Factfinder: is the US Census official browser for data
Social Explorer: is a faster alternative to the census data, though the geographies of what you can get are a little more limited. Choose "Reports" to explore the data tables, or use the Map browser to quickly see some data represented.
Census TIGER Products: is an official US Census set of products offering legal and statistical areas, including many census geographies. A number of products are available, including prepackaged geodatabases containing boundaries and commonly used tables.
While both Social Explorer and American Factfinder allow some exploration of historic data, the NHGIS or National Historic GIS project provides historic census boundaries in a form that works beautifully with their tables in GIS products. You have to sign up for an account, and agree to use the data for good, not evil, but it is a free source for researchers.