The Council on Foreign Relations reports:
"Some time in mid-to-late October, the U.S. Census Bureau’s population clock will roll past the 300 million mark. Though it is the world’s third-most populated nation, the United States is far behind the first two, China and India.
Still, the birth—or immigration—of the 300 millionth American comes at a time when significant demographic changes pose new domestic challenges within the United States (USNews). A burgeoning populace raises a host of questions about the environment, the economy, and energy consumption. These, coupled with the societal stresses of increased immigration, ensure that all 300 million of us will realize the old maxim of living in interesting times."
There are obviously remaifications for the US. This interesting piece addresses some of them.