From the United States Census:
As our nation prepares to ring in the new year, the U.S. Census Bureau projects the U.S. population will be 326,971,407 on Jan. 1, 2018.
This represents an increase of 2,314,238, or 0.71 percent, from New Year’s Day 2017. Since Census Day (April 1) 2010, the population has grown by 18,225,587, or 5.90 percent.
In January 2018, the United States is expected to experience one birth every 8 seconds and one death every 10 seconds. Meanwhile, net international migration is expected to add one person to the U.S. population every 29 seconds. The combination of births, deaths and net international migration will increase the U.S. population by one person every 18 seconds.
The projected world population on Jan. 1, 2018, is 7,444,443,881, an increase of 78,521,283, or 1.07 percent, from New Year’s Day 2017. During January 2018, 4.3 births and 1.8 deaths are expected worldwide every second.
Direct to Interactive Data Visualization: U.S. Population Up 5.90% Since the 2010 Census (April 1, 2010 to January 1, 2018)
Direct to U.S. Population Clock