You know how things work. In order to prove anything to some people, you have to have data. And that means numbers. One of our favorite sources of data is the Statistical Abstract of the United States. We just received the 2008 edition, which, in reality, gives you stats for 2005 or 2006 and sometimes several years earlier.
There’s an electronic version on the U.S. Census Bureau’s web site that goes all the way back beyond 1878. Compare and contrast the number of post offices (1878: 39,258 – 2006: 36,826) or coal production (1878: 49,130,584 tons – 2005: 1,133,000,000 tons.) Astonish your friends with your storehouse of scintillating factoids.