The United Nations estimates that the current population of the U.S.A. is 328,843,550. That means it holds 4.27% of the world's total population. According to this statistics, the urban population is 83.9% of the total population of the country, that means around 276,062,331 people. This is an increase form the 2010 census in which 80.7% of U.S.A population lived in urban areas. It is important to say that this are all estimate, based on the data from tthe 2010 census. Remeber that this census is done every 10 years.