During the past month, hundreds of migrants nabbed by the border patrol after illegally crossing the US-Mexico border through Texas have been flown to Arizona and left at Greyhound Bus stations in Tucson and Phoenix.

This has drawn criticism from activists on both sides of the immigration debate. Immigration advocates accuse the federal government of releasing migrants without providing enough basic necessities such as food and water on days when temperatures hover around 100 degrees F.

The immigrants are being sent to Arizona, since it has more processing capacity. It’s unclear whether the transfers will continue, but the Arizona governor is furious.

Arizona Gov. Jan Brewer (R) calls it “another disturbing example of a deliberate failure to enforce border security policies and repair a broken immigration system” in a letter to President Obama.

Texas is replacing Arizona as the busiest sector for illegal border crossings. In fiscal 2013, agents in the Rio Grande sector caught 154,453 migrants, up from 97,762 the previous year.

In Arizona’s Tucson sector, agents recorded 125,942 arrests last year, says Andy Adame, a Border Patrol spokesman. Many of the migrants coming to Texas are from Central America and are coming as families. Various studies conclude that crime, gangs, and poverty are driving people from countries south of the border.

Children have also been increasingly coming alone, too. From October to May, 33,470 of the 47,017 unaccompanied minors caught along the entire Southwest border crossed through the Rio Grande Valley.

On Monday, Mr. Obama described the influx as an “urgent humanitarian situation” that called for a swift response. Federal agencies are moving to provide temporary housing and other services.

Immigration authorities won’t say whether Arizona should expect more arrivals from Texas, but in a Friday statement, Gov. Brewer said some 1,100 unaccompanied children will be transported here over the weekend.

Bob Dain, a spokesman for the American Federation for Immigration Reform, which promotes tighter immigration controls, blasted the Obama administration for its handling of the latest wave of illegal border crossings.