The contract, which calls for cameras, sensors and even unmanned planes, is the first part of a multibillion-dollar government plan designed to reduce illegal entry along the 6,000 miles of the Canadian and Mexican borders.
The final price tag for the so-called Secure Border Initiative is unknown, but Homeland Security officials disputed published reports saying the cost could exceed $2 billion.
"What we are looking to build is a 21st century virtual fence," Homeland Security Secretary Michael Chertoff said at a news conference announcing the contract award.
He and other officials stressed that the initial three-year contract, which focuses on a 28-mile stretch of border near Tucson, Arizona, could be adapted as circumstances change.
"The border is not uniform. It's a complicated mix" of urban and remote areas, ranging from high desert in the Southwest to heavily forested area in the Northwest, Chertoff said.
"We don't want to lock ourselves in" to any one technology, he said.
Officials expect Boeing and its corporate partners to begin operating the Tucson-area project by next spring, Chertoff said.
Chicago-based Boeing was among several major defense companies competing for the job. While other companies' proposals relied more heavily on using flying drones to patrol the border, Boeing focused on a network of 1,800 high-tech towers, equipped with cameras and motion detectors.
The Secure Border Initiative is the government's latest attempt to use advanced technology to solve the illegal immigration problem, which has received new attention as a security issue since the Sept. 11, 2001, terrorist attacks.