At the Puerta Este border crossing, U.S. citizens and other foreigners walking into Mexico must now show their passports.

Mark Bolzern traveled 3,700 miles to go to the dentist. The 56-year-old Anchorage, Alaska, native left home this spring, made a pit stop in Las Vegas to pick up a friend, and kept heading south, all the way to Los Algodones, Mexico, a small border town teeming with dental offices.

The Arizona Chamber of Commerce and Industry is proud to have played host earlier this year to events featuring three of the leading Republican presidential contenders: Wisconsin Gov. Scott Walker, Florida Sen. Marco Rubio and former Florida Gov. Jeb Bush. I expect we will welcome additional candidates from both parties in the fall.

Two environmental groups filed a lawsuit Tuesday aimed at forcing the federal government to protect Arizona’s diminishing cactus ferruginous pygmy owl population under the Endangered Species Act.

The number of immigrants in the U.S. illegally has stopped growing for the first time since the 1980s, another sign of the success of border-security efforts, the head of Homeland Security said Oct. 9.

The Arizona State Trade and Investment Office has opened in Mexico City. Gov. Jan Brewer's says it's the latest major effort by the state to strengthen and secure economic ties with Arizona's largest trading partner.

Authorities are testing water from the San Pedro River in southern Arizona that may be contaminated with toxic waste that traveled north after a massive copper mine spill in Mexico this summer.

The number of immigrant children caught alone illegally crossing the Mexican border into the United States continued to decline in August, according to figures disclosed Wednesday by the Homeland Security Department.

A Border Patrol official who was removed from his position in June is accusing the agency of covering up "highly suspect" deaths in clashes along the southern border.

Border security and illegal immigration have become dominant issues in the Republican primary for governor as some accuse their opponents of making unrealistic promises that they can’t keep.