@Bronson Simmons- There's a good book called Buy It, Rent It, Profit!: Make Money as a Landlord in Any Real Estate Market by Bryan M. Chavis. It does a pretty good job of giving you a frame work for organizing information. The author called it SEOTA or Strategic Evaluation Of Target Area. I credit this book for giving me a solid frame work and helping me pick the right property types and areas.
The US Census is actually one of my top sites for getting high level data. Follow this link. Type in either the city name or zip code. From there you search the tables and filter the data you actually want. I'm by no means an expert on searching the site, but I I'm able to find what I need without too much trouble.
You can also go to sites like City Data, world population review, city protect.
For more specific data try the city's home page site or googling for specific studies. Chicago for example has community data snapshots.
Lastly BP can be an excellent source for more neighborhood specific information.