Did you know that in 1870 there were only two women in the entire state of Colorado who were employed in the manufacturing industry? U.S. census information dating almost as far back as the drafting of the Constitution is available for free online at the United States Historical Census Data Browser put out by the University of Virginia. The site includes census information about the people and economy of every state and county from 1790 to 1960. Visitors can create their own charts and graphs, based on criteria they select in categories such as agriculture, religion, manufacturing, literacy, education, slave populations and marriage. The sheer amount of comparative data should fascinate any history buff.