> ... it would be useful to mark a few more major cities on the map.

It would. And some of the ones that are marked are kinda pointless. Anyone with any knowledge of U.S. geography can find New York, San Jose, and Seattle by the shape of the coastline. But what about Salt Lake City, Kansas City, Memphis, Omaha, Louisville, Indianapolis, St. Louis, etc.

Regardless, very nice visualization.

More cities show up if you click to zoom in. Some cities may take a few zoom levels to show up, though, like my native Amarillo.