As of July 2013, the population of the United Stated was estimated to be just over 316 million people. In October 2014, the U.S. Census Bureau estimated that the population had surpassed 319 million.
Because people die and give birth at a constant rate, the population of the United States is always in flux. The United States is the third most populous country in the world behind China and India, which each have populations in excess of 1 billion. Between 2010 and 2013, the population of the United States increased by about 2.4 percent. Slightly more than half of the United States population is female. Nearly one-quarter of the population is under the age of 18.