Agent on horseback watches over illegal immigrants.            Border patrol agents on horseback in Arizona.


Border Patrol observation tower with camera along Mexican border in Arizona.


A Black Hawk helicopter lands on a public highway so its crew can pursue illegal immigrants near Three Points. The Black Hawk, long a staple of Army air operations, now is a cog for the Customs Service, whose officers are participating in joint air operations across southern Arizona with the Border Patrol, its sister agency.