The size of the U.S. population, as well as its age and sex composition, has significant implications for the economy and the federal budget. In CBO’s projections, the U.S. population increases from 342 million people in 2024 to 383 million people in 2054, growing by 0.4 percent per year, on average, or by less than one-half the pace experienced from 1974 to 2023 (0.9 percent per year). Over the next decade, net immigration accounts for about 70 percent of the overall increase in the size of the population, and the greater number of births than deaths accounts for the remaining 30 percent. After 2034, net immigration increasingly drives population growth, accounting for all population growth beginning in 2040.