The total number of immigrants in the U.S. rose to a record high of 51.4 million as of February 2024, representing 15.5 percent of the total population,according to CIS. The U.S. Census Bureau published projections in November which estimated that the share of foreign-born nationals in the U.S. would not reach 15.5 percent until at least 2039, making the projections “obsolete,” CIS authors Steven Camarota and Karen Zeigler wrote.