The Investigative Reporters and Editors website has a special section about the census.
From here, you can download data all the way down to the neighborhood (“place”).
The data can be overwhelming, so you might start with the basic population numbers first. You can also look at easy-to-understand numbers such as “Urban vs. Rural”.
IRE.org also has lots of tipsheets available free to members, and some webinars available for purchase.