The U.S. fertility rate today is 1.78. A rate of 2.1 is needed to maintain the population at its current size.
The U.S. population continues to grow because of immigration. Over the next 70 years, immigration is forecast to account for 90% of U.S. population growth.
Going back to 1950, the U.S. fertility rate peaked at 3.58 in 1958. This is a graphic display of the impact of the post WW 2 baby boom. The chart comes from Macro Trends.
The baby boom echo was much smaller (about 1990 to 2008 or so) because the next generation had fewer kids per family. Yet this still led to a peak in high school graduations around 2008-2010.
UPDATE
Korea’s fertility rate hits 0.81. The population of Korean is expected to shrink to half its current size by end of the current century.
This also illustrates why the U.S. cannot depend on an endless supply of immigrants to address that the U.S.is also now in negative population growth (albeit, nowhere near the level of Korea).
