Population Density of the Continental U.S.

According to the U.S. Census Bureau, the estimated population of the United States surpassed 300 million on October 17, 2006.

Environmental Impact:

• According to the U.S. Census Bureau, the estimated population of the United States surpassed 300 million on October 17, 2006.

• With one birth every 7 seconds, a death every 13 seconds, and a migrant entering the country every 31 seconds, the United States’ population is growing at a rate of one person every 11 seconds.

• The U.S. now joins China and India as the only countries to exceed the 300 million mark in population.

• Top 10 populous U.S. cities (based on U.S. Census Bureau 2005 estimates):

1. New York, NY - 8,143,197

2. Los Angeles, CA - 4,097,340

3. Chicago, IL - 2,842,518

4. Houston, TX - 2,016,582

5. Philadelphia, PA - 1,463,281

6. Phoenix, AZ - 1,461,575

7. San Antonio, TX - 1,256,509

8. San Diego, CA - 1,255,540

9. Dallas, TX - 1,213,825

10. San Jose, CA - 912,332

• America passed the 100 million mark in 1915 and the 200 million mark in 1967.  This makes the increase from 100 to 200 million 52 years, while the increase from 200 to 300 million 39 years, 13 years faster.

• Although the nation's growth rate is larger than that of any other industrialized country in the world, it remains slower than that of developing countries, including India and China.

• The United States consumes a quarter of the world's energy and is the single largest emitter of carbon dioxide in the world.  As the population increases, these numbers will continue to rise.

• For Earth scientists, population density maps can be crucial in answering questions about the relationship between people and the environment. How does population density relate to changes in land cover? How are natural resources distributed in relation to population? How do densely populated regions, with their pollution, artificial surfaces, and urban heat islands, affect climate? To answer these and other questions, scientists compare detailed population maps to other geographically based data sets, including satellite data. In the comparison, trends that track the human footprint can emerge.