A U.S. Border Patrol agent escorts a group of undocumented immigrants into custody with helicopter support from the U.S. Office of Air and Marine on May 20, near the U.S.-Mexico border in Havana, Texas. The Rio Grande Valley area has become the busiest sector for illegal immigration on the whole U.S.-Mexico border with more than a 50 percent increase in the last year.

The Rio Grande snakes between Mexico and the United States, forming the international border on May 21, near Harlingen, Texas. The area is active for drug smugglers bringing their product north from Mexico into the United States.

U.S. Border Patrol agent Ryan Bell looks for drug smugglers on the bank of the Rio Grande at the U.S.-Mexico border on May 21, near Hidalgo, Texas.

Cars drive from Matomoros, Mexico, left, across the U.S.-Mexico border at the Rio Grande on May 21, into Brownsville, Texas. The area is active for legal international commerce as well as drug smugglers bringing their product north from Mexico into the United States.

A U.S. Border Patrol agent searches for drug smugglers near the Rio Grande at the U.S.-Mexico border on May 21, near Hidalgo Texas.

Mexican Army troops stand guard on the Mexican side of the Rio Grande at the U.S.-Mexico border on May 21, near McAllen, Texas.

The Mexican border town of Matomoros is seen on the Rio Grande across the U.S.-Mexico border on May 21, near Brownsville, Texas.

A suspected drug smuggling scout paddles his raft back across the Rio Grande into Mexico from the U.S. side of the border on May 21, near Hidalgo Texas.

The mouth of the Rio Grande releases fresh water into the Gulf of Mexico forming the border between the United States. left,, and Mexico, right, on May 21 at Las Palomas Wetlife Management Area, Texas. The area, popular with tourists as well as wildlife, is also attractive to drug smugglers bringing their product north from Mexico into the United States.

Haitian residents, who have been living and working undocumented in the Dominican Republic wait, for the third day, for Dominican immigration officials to allow them back into the Dominican Republic at the border at Haiti's town of Ouanaminthe on Jan 9, 2013. About 1,000 undocumented Haitians, who returned to their home country for the year end holidays, were prevented from entering back into the Dominican Republic after the Dominican Army increased border control.

Haitian residents wait at the border of the Dominican Republic.

A Haitian boy passes, with help from his father, around the locked gate on a bridge that separates Haiti from the Dominican Republic, to attend school in the Dominican Republic.

Syrians cross the border from the Syrian town of Ras al-Ain to the Turkish border town of Ceylanpinar after an air strike on December 3, 2012.

Syrians try to cross the border from Ras al-Ain to the Turkish border town of Ceylanpinar after an air strike on December 3, 2012.

Syrian refugee children play on slide put up for them in a refugee camp at the Syrian-Turkish border near Azaz, Syria, Oct. 7, 2012. The makeshift refugee camp is reported to be growing daily, housing several thousand refugees under poor sanitary conditions and under the control of the Free Syrian Army.

Syrian refugee boys fill bottles with water in an abandoned storage house which is part of a refugee camp at the Syrian-Turkish border near Azaz, Syria, Oct. 7.

A Syrian refugee woman tends to her crying baby as her family sits on the ground in a refugee camp at the Syrian-Turkish border near Azaz, Syria, Oct. 7.

A Syrian refugee sits amidst a pile of belongings, waiting for permission to enter Turkey, at the Syrian-Turkish border near Azaz, Syria, Oct. 7.

Syrian rebels stand next to their vehicle after seizing control of the Bab al-Hawa border post with Turkey on July 20, 2012. Some 150 armed rebel fighters were in control of the post, which lies opposite Turkey's Cilvegozu border crossing in the southern province of Hatay.

Carcasses of burnt-out lorries at the Bab al-Hawa border post with Turkey are seen on July 20, 2012 after it was seized by Syrian rebels following a fierce battle with Syrian troops.

A broken picture of former Syrian president Hafez al-Assad, Bashar al-Assad's father, is seen at the Bab Al-Hawa border gate after clashes between Syrian rebels and the Syrian army on July 20, 2012.

Syrian rebels walk at the entrance to a building of the Bab al-Hawa border post on July 20, 2012.

Ukrainian border guards take part in a master class in the Borispol airport near Kiev on Friday. Hairdressers and make-up artists conducted master classes for Ukrainian border guards who will meet tourists at Ukraine's main air hub during the Euro 2012 football championship.

A Ukrainian border guard takes part in a master class in the Borispol airport near Kiev.

Ukrainian border guards chat as they take part in a master class in the Borispol airport.

Ukrainian border guard working at the Borispol airport near Kiev.

Ukrainian border guards and a sniffer dog are seen in the Borispol airport near Kiev.

California, U.S.

Arizona, U.S.

Arizona, U.S.

State of Baja California, Mexico

California, U.S.

California, U.S.