1. The population of the United States is approximately 400 million, with a concentrated distribution primarily along the East and West coasts.2. Key cities on the East Coast include Washington, D.C., New York, Philadelphia, and Boston, among others.3. On the West Coast, major cities are represented by California, Los Angeles, San Francisco, and Seattle, among others.4. Additionally, there is a smaller population distribution in the central regions and in the state of Hawaii.