Is there any place available online to go and get demographics on an area, when considering investing in city, town or neighborhood?

Thanks.

census.gov

look at future land use planin the county courthouse,then look at building permit departments and planning and zoning.Usually if you see wal-mart or walgreens,or the major restaurants are coming in it means they have paid tens of thousands to perform there own in-depth feasibility studies and determined it's a good area to build there.They have already looked at projected traffic counts,migration patterns,infrastructure,etc.
good luck