I gave this link to someone else last night, it's rather interesting. It's from the US census.
https://www.census.gov/content/dam/Census/library/publications/2020/demo/p25-1144.pdf

Beginning in 2030, net international migration is expected
to overtake natural increase
as the driver of population
growth in the United States
because of population aging.
That year, the United States
is projected to add 1 million
people by natural increase
(the number of births minus
deaths) but 1.1 million through
net international migration.
Because the number of deaths
is projected to rise substantially, in 2060 the U.S. population is projected to add about
500,000 people by natural
increase, whereas net international migration is expected
to add more than twice that
number—1.1 million—to the
population.
• The population is projected
to grow more from international migration than natural
increase in coming decades
because of population aging.
As baby boomers age into
older adulthood, the number
of deaths is projected to rise
faster than the number of
births. As a result, the population will naturally grow very
slowly, leaving international
migration to overtake natural
increase as the leading cause
of population growth, even as
projected levels of migration
remain relatively flat.

This is why I'd guess they are doing a lot of what they call "paroling" of migrants into the US. That allow them to work. The rest who don't get parole will work illegally, all unclaimed taxes paid into the system that no one collects but the federal, state and local governments.