As one of the few countries in the world, the US has Birthright citizenship (if you were born here, you are automatically a US citizen).
The Trump administration has wanted for a long time Birthright citizenship abolish, because pregnant illegals abuse this by getting their child on American soil:
In other words, an illegally present mother gives birth to an American citizen. Actually a kind of anchor with which she hooks herself in the US.
While the birthright citizenship case has yet to be heard by the Supreme Court, Trump struck a deal with Mexico some time ago that would require “asylum seekers” in Mexico to wait for permission to enter the US.
Before that, “asylum seekers” / illegal immigrants first entered the US, received a letter asking to come to court on a certain date regarding their stay in the US, and subsequently did not appear in court.
In addition, heavily pregnant illegal immigrants used this waiting time in the US as an opportunity to get their "anchor baby" in the US. Once the child is born in US territory, the mother is almost impossible to deport because her child is a US citizen.
If, as a highly pregnant woman, you try this NOW illegally, it is almost impossible. You are now waiting in Mexico for your trial and you will be scheduled for an appointment at a US immigration court AFTER your birth, not before, to prevent abuse of Birthright citizenship.
Today in the US there are 4.5 million anchor babies, under the age of 18, in a population of 73.4 million children aged 0-17. So 6.1% of children are achor-baby / child /
Trump stops abuse of birthright citizenship, along with Mexico
4.5 million anchor babies / children in the US
US Census Bureau, US population by age