Social Explorer just relaunched their site with enhanced interactive maps and additional content such as U.S. historical census data back to 1790.

You’ll want to give it a try — Social Explorer data now includes:

• US Census from 1790 to 2010
• All annual updates from the American Community Survey (ACS)
• InfoGroup data on religious congregations for the United States
• Religious Congregations and Membership Study from 1980 to 2000
• Carbon Emissions data for 2002 from the Vulcan Project
• Updates to ACS and Census 2010 data including urban supplement and Census Zip Codes (ZCTAs)
• County-based Religion Data

 New Functionality includes:

• Ability to save, share, and embed interactive maps and projects for blogs, Facebook, Twitter, and other social media. 
• Ability to map all of the tracts in the US and chose what layer to map
• Ability to turn map layers on and off
• Improved street files
• A select by radius tool
• Geocoder works with fuzzy logic
• Variables can be displayed through shaded area, bubbles, or dot density maps

This tutorial will help get you started!