Big boom.

The United States is about to pass a major milestone. The U.S. Census Bureau predicts that the nation's population will top 300 million this month.

Every year, the number of births and immigrants entering the U.S. dwarfs the number of deaths in the country. As a result, the U.S. population is growing by roughly one person every 10 seconds. That's the fastest growth rate of any industrialized nation.

This population boom may not be cause for celebration. Every person on Earth consumes natural resources such as water and food. In addition, most people use nonrenewable fossil fuels to create energy. A ballooning population drains these resources.

An ecological footprint is an estimate of the area of land and water needed to provide resources to support one person. Individuals in industrialized countries, such as the U.S., tend to use a lot of energy and therefore have a large ecological footprint. The footprint of a U.S. resident is roughly equal to the footprints of how many individuals living in India?