The office projects 364 million people living in the United States in 2056, up from the current population of around 349 million.

The population growth will be 0.3 percent on average in the next 10 years, but will go down to an average rate of just 0.1 percent between 2037 and 2056, CBO projects.

The population projection is down 2.1 percent from the 372 million CBO estimated in a January 2025 report, and the 383 million it projected in a 2024 estimate.

The drop stems from declining fertility rates and lower numbers of immigrants coming to the country, according to the budget office.

For a generation to replace itself in the absence of immigration, the fertility rate needs to be 2.1 births per woman.