The Homeland Security Department is constantly searching for solutions that will protect the United States' borders and preserve the lawful flow of commerce while not overwhelming the federal budget. The border of the U.S. has a long history with technology that dates back to the former Immigration and Naturalization Service (INS), who began using surveillance technologies in the 1970's when low-light video cameras were installed at the border. For the past four decades, video cameras and infrared sensors have been used to detect and deter illegal immigrants without the cost of hiring additional border patrolmen.

Surveillance technology took a huge leap with the development of the Integrated Surveillance Intelligence System in 1997 that deployed around 13,000 ground sensors by the year 2000. There were four main types of sensors installed along the border: seismic, magnetic, motion, and infrared. However, these sensors proved to be inadequate at differentiating animals from humans and commonly failed under harsh weather conditions. Since then, the Department of Homeland Security (DHS) has tried other formulas for using technology to safeguard the border. The "America's Shield Initiative", proposed by the DHS in 2004, was soon replaced by the multi-year plan, the "Secure Border Initiative" (SBI). The SBI is a multi-billion dollar plan that proposes to place more agents to patrol the borders and secure the ports of entry, to upgrade the technology used in controlling the border, and to greatly increase the investment in infrastructure improvements at the border.

Some of the proposed technology advances of the SBI include using more Unmanned Aerial Vehicles (UAVs), Remote Video Surveillance cameras and sensors, and aerial assets. But with the limitations on full deployment, it is unlikely that the Secure Border Initiative will be able to meet its expectations of creating a secure entry-exit system combined with a surveillance/patrol dispatch system. Without a secure entry-exit system that can identify visa abuse and travel document fraud, even the best technology available will not be effective in lowering the number of illegal immigrants and terrorists.

At one time, Congress proposed building a border fence along the entire U.S.-Mexico border after discovering that a state-of-the-art fence along the border in western San Diego County was effective in reducing the number of Border Patrol arrests. Congress and the Department of Homeland Security were strongly considering the border fence despite its high price because it promised to deter some of the 500 million people that cross the borders each year. A study by the nonpartisan Congressional Research Service showed that the price of building and maintaining a double set of steel fences along the U.S.-Mexico border could cost as much as $49 billion for its expected life span of 25 years. Secure fencing of various kinds already exists along 106 miles of the border, but this new fence would stretch along 700 miles of the border. Because of its high economical cost, the steel fence was never built.

In 2007, the SBI attempted to pass a measure to implement a combination of surveillance technologies, dispatching systems and data analysis systems, a bill that the Senate calls a "virtual fence". Homeland Security has contracted Boeing Co. to construct a "virtual fence" that will run along all 6,000 miles of the U.S. border, a security measure that is expected to cost only $2.5 billion.

Even if a "virtual fence" is installed along the entirety of the U.S.-Mexico border, it is still not guaranteed to be effective in lowering illegal immigration. It has been estimated that approximately 45% of the illegal immigrants in the U.S. entered legally through ports of entry and did not return when their visas expired. Immigrants from Mexico can also bypass the virtual fence by entering the U.S. illegally through Canada. The U.S.-Canada border is almost four times longer than the length of the U.S.-Mexico border, and extending the virtual fence to cover this distance as well would be extremely expensive. In order for the entry-exit system to be effective, there must a seamless integration between all systems along all ports and borders leading into the United States. Case in point: Congress has recently decided to cancel the SBI and to back out of their contracts with Boeing and Raytheon. Instead, the U.S. will begin to use surveillance systems, thermal imaging, UAVs and other technological equipment from the commercial market.