Keir Clarke built an interactive map that shows the top ten U.S. cities for every decade’s census from 1790. Included is a changing list of the cities and a red marker showing the country’s geographical population center. As you click through the decades, you can see it move west. The list itself is interesting. The number one city never changes, but others jump on and off the top ten. While New York City stays at the top, Brooklyn was also on the top ten through most of the 19th century. The interactive map is here, and you can read about how the map was created at Maps Mania.