Mexico has sent 3,653 migrants back to their home countries in the past five weeks, almost emptying government migrant centres in an effort to contain the spread of coronavirus.
The migrants came from countries including Guatemala, Honduras and El Salvador. Only 106 remain in government facilities, official data showed on Sunday.
Victor Clark Alfaro, a migration expert at San Diego State University, said the announcement went hand in hand with the Mexican government's efforts to keep migrant numbers in check under pressure from US President Donald Trump.
"Today, Mexico's policy is to contain and deport," he said.
Last week, Mr Trump announced plans to temporarily halt immigration to the US for 60 days during the coronavirus crisis.
Mexico's National Migration Institute said that since March 21, to comply with health and safety guidelines, it removed migrants from its 65 facilities, which held 3,759 people last month.
The institute's migrant centres and shelters have space for 8,524 people, it said.
There are dozens of other shelters run by a variety of religious and non-government organisations throughout the country that continue to harbour migrants.
Among those who remained in the centres run by the institute were migrants awaiting the outcome of asylum requests or judicial hearings, as well as others who sought permission to stay, a migration official said.
The vast majority of those sent back were migrants detained by authorities because they were in Mexico illegally, the official said.
Some of the migrants no longer wished to stay in centres because of the risk of becoming infected with the virus, the official said.
Most of the migrants passing through Mexico to reach the US border are from Honduras, Guatemala and El Salvador.
More than 80 Guatemalan migrants deported to their homeland from the US tested positive for coronavirus.
