Before we take a look at how our built environment has evolved, let's look at current growth patterns in the U.S. What are current growth rates? Where have we traditionally set up our homes and businesses? Where has man's built environment had the greatest impact on the natural environment?

The U.S. population is growing and changing rapidly.
Our population has grown by leaps and bounds over the last century -- from seventy six million in the year nineteen hundred to over two hundred eighty two million in the year two thousand.

In two thousand and six, we passed the three hundred million mark. And we are on our way to four hundred million by two thousand forty.

That's unprecedented growth.

Currently, eighty three percent of us live in urban or metropolitan setting. Urban populations, too, are soaring: among metro areas of one million plus residents, six grew by more than thirty percent in the nineteen nineties; sixteen grew by more than twenty percent and thirty one grew by more than ten percent.