Illegal border crossings are on the rise: 7,500 migrants were stopped on Sunday alone

The number of migrants illegally crossing the U.S.-Mexico border has risen steadily since the start of September, according to two Department of Homeland Security officials, with Border Patrol apprehending more than 7,500 migrants on Sunday alone.

In July, the latest month for which official data is available, the number of daily apprehensions of illegal border crossers averaged just over 4,300.

The rise in migrants may indicate that new policies put in place by the Biden administration in May, which initially kept numbers low, may now be having less of an impact.

The new policies make it harder for migrants to seek asylum at the U.S.-Mexico border and easier for them to seek lawful entry to the U.S. from their home countries, a new strategy the Biden administration enacted after Covid-19 border policies expired in mid-May. Before the policy change, daily apprehensions of illegally border crossers had reached a record high of more than 10,000.

A U.S. Customs and Border Patrol agent arrives to pick up a family of five in the Tucson Sector of the U.S.-Mexico border (Matt York / AP file)
A U.S. Customs and Border Patrol agent arrives to pick up a family of five in the Tucson Sector of the U.S.-Mexico border (Matt York / AP file)

“We remain vigilant and expect to see fluctuations, knowing that smugglers continue to use misinformation to prey on vulnerable individuals," a Customs and Border Protection spokesperson said.

"CBP is working according to plan and as part of our standard processes to quickly decompress the areas along the southwest border, and safely and efficiently screen and process migrants to place them in immigration enforcement proceedings consistent with our laws."

Certain sectors of the border have been affected more than others.

On Sunday, the busiest sector was the Rio Grande Valley, Texas, with more than 1,800 apprehensions; followed by Del Rio, Texas, with more than 1,600 apprehensions; Tucson, Arizona, with more than 1,500; and El Paso, Texas, with more than 1,000, according to data obtained by NBC News.

Fox News reported 2,200 migrants crossed in the Del Rio Border Patrol sector into Eagle Pass Texas between midnight and 10 a.m. Monday. NBC News has not independently confirmed that account.

Areas like Del Rio, which is remote and not supported by as many charities that can shelter migrants, are more easily overwhelmed by a sharp increase in migration.

Two years ago, nearly 30,000 Haitian migrants converged under a bridge after crossing from Mexico into Del Rio.

In Tucson and San Diego, Border Patrol began releasing migrants onto the streets to alleviate overcrowding in shelters last week.

In Rio Grande Valley and Tucson, the number of migrant children crossing with and without adults is on the rise.

Border Patrol agents in Rio Grande Valley saw, on average, 150 unaccompanied children each day last week, according to the two DHS officials, up from a daily average of 94 in June, as reported in public data.

This article was originally published on NBCNews.com