I found this by way of Andrew Sullivan. This is an animated graph from Ian Stevenson showing global immigration trends to the United States since 1820. Each dot is 100 people. Look at how many people have come to the U.S. from all over the world. As Sullivan says, no other country attracts people the way the U.S. does. The only thing that has changed is where the people are coming from and where’ they’re settling. Look at how many European immigrants came to the Iron Range and Minnesota in general from the late 1800s through mid 1900s. It means something more when you see it animated.
Reading the comments at Stevenson’s site led me to flowingdata.com, which has all sorts of statistical goodies for human trends.