At midnight tonight a Covid era rule to prevent immigration is set to expire with lawmakers and migrants alike unsure as to what comes next.
As US officials scramble to bring in new restrictions to replace 'Title 42' which expires tonight at 12am in the US, thousands of migrants are trying to cross the border.
Families have been seen trying to swim across the Rio Grande on the US' southern border, throwing on dry clothes at the other side, before picking their way through the hastily erected barbed wire fences.
A heart-breaking picture shows a distraught mother trying to get her daughter across the river and back to the Mexican side after being turned away by US border guards.
But what is Title 42 and why is this rule having such dramatic consequences on the Mexico-US border?
Title 42 of a 1944 public health law allows curbs on migration in the name of protecting public health.
It was brought in during the Covid-19 pandemic in an attempt to stop the virus spreading.
It has allowed US authorities to quickly expel migrants at the border for the past three years but it expires at midnight on Thursday (May 11).
Due to congressional log jams, no immigration reform has been passed in decades.
Title 42 is a holdover from the Trump administration, which began in March 2020.
Before that migrants could cross illegally, ask for asylum and be allowed into the U.S. They were then screened and often released to wait out their immigration cases.
Under Title 42, migrants were returned back over the border and denied the right to seek asylum in the US.
Migrants were turned away 2.8 million times under Title 42, families and children travelling alone were exempt.
But there were no real consequences, except to turn people around.
So migrants were able to try again, and again to cross the border illegally on the off chance that they would get into the U.S.
President Joe Biden initially kept Title 42 in place after he took office, then tried to end its use in 2022.
Republicans sued, arguing that the restrictions were necessary for border security - courts had kept the rules in place.
But the Biden administration announced in January that it was ending national COVID-19 emergencies.
The restrictions will end 11.59pm EDT on Thursday.
New policies that crack down on illegal crossings are set to come in.
From midnight migrants caught crossing illegally will not be allowed to return for five years. They can face criminal prosecution if they do.
This doesn't mean the US will stop taking in migrants.
Authorities have said they will accept up to 30,000 per month from Venezuela, Haiti, Nicaragua and Cuba as long as they come by air, have a sponsor and apply online first.
They will also allow up to 100,000 people from Guatemala, El Salvador, and Honduras into the U.S. who have family here if they, too, apply online.
The Biden administration will be turning away anyone seeking asylum who didn’t first seek protection in a country they travelled through, or first applied online.
This is a version of a Trump administration policy that was overturned by the courts, so it’s not clear whether this restriction will hold up - a lawsuit is expected.
Because of the uncertainty thousands of migrants are rushing the border before the new rules come in.
