The U.S. has nearly 305 million people today. The new census projection is US population to hit 400 million in 2039 and 439 million in 2050. The previous middle projection was 392 million in 2040.
The new census projection is that white people will no longer make up a majority of Americans by 2042, according to new government projections. That's eight years sooner than previous estimates, made in 2004.
By 2050, whites will make up 46 percent of the population and blacks will make up 15 percent, a relatively small increase from today. Hispanics, who make up about 15 percent of the population today, will account for 30 percent in 2050, according to the new projections. Asians, which make up about 5 percent of the population, are projected to increase to 9 percent by 2050. The population 85 and older is projected to more than triple by 2050, to 19 million.
This site thinks there are still undercounts of illegal immigrants, underestimated lifespans and that the higher estimates for US population will prove to be more accurate.
The high series estimate for the census bureau is in table C of this PDF from 1996 on page 5. It projects 295 million in 2005, 314 million in 2010, 357 million in 2020, 405 million in 2030, 458 million in 2040 and 519 million in 2050.