Where can I get a map of St. Louis that shows demographic Census information?
I would suggest Social Explorer database as a starting point. It allows for the interactive mapping of demographic census data from 1790 to the present. You can map detailed information about St. Louis from 1940 to the present.
These professionally created race & ethnicity maps using 2000 census data, include a map of St. Louis: http://www.flickr.com/photos/walkingsf/sets/72157624812674967/
To learn more about the Census and demographic mapping, see our Census Research Guide, which includes contact information for our resident Census expert.