From the U.S. Census:
As our nation prepares to ring in the new year, the U.S. Census Bureau today projected the U.S. population will be 324,310,011 on Jan. 1, 2017.
This represents an increase of 2,245,347, or 0.70 percent, from New Year’s Day 2016. Since Census Day (April 1) 2010, the population has grown by 15,564,473, or 5.04 percent.
In January 2017, the United States is expected to experience one birth every 8 seconds and one death every 11 seconds.
Meanwhile, net international migration is expected to add one person to the U.S. population every 33 seconds.
The combination of births, deaths and net international migration will increase the U.S. population by one person every 17 seconds.
The projected world population on Jan. 1, 2017, is 7,362,350,168, an increase of 77,849,375, or 1.07 percent, from New Year’s Day 2016. During January 2017, 4.3 births and 1.8 deaths are expected worldwide every second.
Direct to U.S. and World Population Clock