WASHINGTON (AP) — The U.S. is putting new restrictions into place at its southern border to try to to stop migrants from crossing illegally and encourage them instead to apply for asylum online through a new process.

The changes come with the end of coronavirus restrictions on asylum that have allowed the U.S. to quickly turn back migrants at the U.S.-Mexico border for the past three years. Those restrictions are known as Title 42, because the authority comes from Title 42 of a 1944 public health law allowing curbs on migration in the name of protecting public health.

Disinformation has swirled and confusion has set in during the transition. A look at the new rules (and the old ones):

WHAT IS TITLE 42 AND WHAT DID IT DO?

Title 42 is the name of an emergency health authority. It was a holdover from President Donald Trump’s administration and began in March 2020. The authority allowed U.S. officials to turn away migrants who came to the U.S.-Mexico border on the grounds of preventing the spread of COVID-19.

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 over the border and denied the right to seek asylum. U.S. officials turned away migrants more than 2.8 million times. Families and children traveling alone were exempt.

But there were no real consequences when someone illegally crossed the border. So migrants were able to try again and again to cross, on the off chance 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 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, and so the border restrictions have now gone away.

Biden has said the new changes are necessary, in part because Congress has not passed immigration reform in decades.

SO WHAT’S HAPPENING NEXT?

The Title 42 restrictions lifted at 11:59 p.m. EDT Thursday.

The Biden administration has put into place a series of new policies cracking down on illegal crossings. The administration says it’s trying to stop people from paying smuggling operations to make a dangerous and often deadly journey.

Now there will be strict consequences. Migrants caught crossing illegally will not be allowed to return for five years and can face criminal prosecution if they do.

NEW ASYLUM RULES

Under U.S. and international law, anyone who comes to the U.S. can ask for asylum. People from all over the world travel to the U.S-Mexico border to seek asylum. They are screened to determine whether they have a credible fear of persecution in their homeland. Their case then goes to the immigration court system to determine if they can stay in the U.S., but that process can take years. Usually they are released into the U.S. to wait out their cases.

The Biden administration is now turning away anyone seeking asylum who didn’t first seek protection in a country they traveled through, or first applied online. This is a version of a Trump administration policy that was overturned by the courts. Advocacy groups sued to block the new rule minutes before it took effect.

The lawsuit, filed in federal court in San Francisco by the Center for Gender & Refugee Studies and other groups, alleges the Biden administration “doubled down” on the policy proposed by Trump that the same court rejected. The Biden administration has said its new rule is substantially different.

WHO’S ALLOWED IN?

The U.S. has said it will accept up to 30,000 people per month from Venezuela, Haiti, Nicaragua and Cuba as long as they come by air, have a sponsor and apply online first. The government also will 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. Border officials will otherwise deport people, including turning 30,000 per month from Venezuela, Haiti, Nicaragua and Cuba who will be sent back over the border to Mexico.

Other migrants also may be allowed in if they apply through the CBP One app. Right now, 740 people per day have been allowed in using the app, which is being increased to 1,000 per day.

WHAT ABOUT FAMILIES?

Families crossing the border illegally will be subject to curfews and the head of household will have to wear an ankle monitoring bracelet. Immigration officials will try to determine within 30 days whether a family can stay in the U.S. or be deported. Usually the process would take years.

The Biden administration considered detaining families until they cleared initial asylum screenings but opted instead for the curfews, which will run from 11 p.m. to 5 a.m. and begin soon in Baltimore; Chicago; Newark, New Jersey; and Washington, D.C., according to a U.S. official who spoke on condition of anonymity because the information was not intended to be public. Families who do not appear for their screening interviews will be picked up by immigration authorities and deported.

OVERCROWDING

Border Patrol stations are meant to house migrants temporarily and don’t have capacity to hold the volume of people coming. Some stations are already too crowded. As a result, agents began releasing migrants into the U.S. with instructions to appear at an immigration office within 60 days or face deportation.

Agents were told to begin releases in any area where holding facilities were at 125% capacity or the average time in custody exceeded 60 hours. They also were told to start releases if 7,000 migrants were taken into custody across the entire border in any one day.

That’s already happened, with some 10,000 people taken into custody on Tuesday. This could create problems for Biden administration officials trying to crack down on those entering the country.

Florida filed a lawsuit claiming the releases violate an earlier court ruling. Late Thursday, a federal judge agreed and at least temporarily halted the administration’s plan for releases. Customs and Border Protection said in a statement that it would comply with the court order, while also calling it a “harmful ruling that will result in unsafe overcrowding … and undercut our ability to efficiently process and remove migrants.”

MIGRATION HUBS

U.S. officials plan to open 100 regional migration hubs across the Western Hemisphere, where people can seek placement in other countries, including Canada and Spain.

There will be hubs in Colombia and Guatemala, but it’s not clear where others will be or when they will be up and running.

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Associated Press Writers Rebecca Santana in Washington and Elliot Spagat in San Diego contributed to this report.