Washington - U.S. immigration officials reported nearly 2 million migrant encounters along U.S. borders nationwide in fiscal 2021, often cited by officials as the highest annual total on record. It's a trend that immigration experts say is the result of repeated entry attempts because of an emergency health order known as Title 42, which denies most migrants a chance to request asylum under U.S. law on public health grounds.

While much of the attention in 2021 was focused on border crossings by families and unaccompanied minors - some barely older than toddlers - the largest cohort of migrant arrivals and expulsions were single adults.

Every month, the U.S. Customs and Border Protection (CBP) releases enforcement data to explain what is happening at the U.S. borders, which includes apprehensions, encounters and removals, among other actions. But what do those terms mean?

Apprehensions

CBP defines an apprehension as 'the physical control or temporary detainment of a person who is not lawfully in the United States, which may or may not result in an arrest.'

Migrants - often in large family groups - who cross U.S. borders outside official ports of entry requesting asylum are temporarily apprehended and eventually expelled from the U.S. back to their countries of origin.

In its monthly reports before March 2020, CBP listed apprehensions individually. But after March 2020, when the Trump administration imposed the Title 42 health order, CBP created a new category called "encounters," which combined apprehensions and expulsions.

Encounters

Migrants who are either apprehended and expelled from the country or were apprehended but allowed to go through routine removal proceedings, which includes seeking asylum while in the U.S., are categorized as encounters.

Cesar Cuauhtemoc Garcia Hernandez, a professor at the Moritz College of Law at Ohio State University and an expert on migration studies, told VOA that apprehensions are a type of encounter.

"When somebody, for example, presents themselves at a port of entry requesting admission into the United States, and then they're turned back because they're inadmissible, then that counts as an encounter," he said.

He explained that migrants who were expelled under Title 42 can be encountered multiple times and counted each time.

Expulsions

Migrants can be expelled from the country after they have been detained at the border under Title 42. They are taken to the port of entry closest to where they entered and are sent back across the border. Expulsion is not the same as deportation, which is a legal process. An expulsion can take hours or sometimes days.

Expedited removals

This process gives immigration officers the power to deport certain noncitizens quickly and efficiently without a hearing before a U.S. immigration judge.

Expedited removals can apply to migrants while they are being processed at a port of entry, or have entered the United States unlawfully, or who cannot prove they have been in the country for at least two years. The guideline can also apply to immigrants who have committed fraud or misrepresentation.

Immigration officers can apply expedited removal to individuals who entered the U.S. without authorization and were encountered within 100 miles of the Mexican or Canadian borders and apprehended within two weeks of arrival into the U.S.

Deportations

In a deportation process, U.S. Immigration and Customs Enforcement formally accuses a noncitizen of being removable. People who are placed in deportation proceedings have the right to legal representation and the right to present a case in front of an immigration judge, who will decide whether to give a departure order.