THE GOVERNMENT ACCOUNTING OFFICE LOOKS AT SECURITY SURVEILLANCE TECHNOLOGIES DEPLOYED ON THE SOUTHWEST BORDER: This is a detailed pdf. The title is a fair summary: “Southwest Border Security: Border Patrol Is Deploying Surveillance Technologies but Needs to Improve Data Quality and Assess Effectiveness.”

One of the conclusions:

Since 2005, Border Patrol has spent more than one billion dollars deploying technologies to the southwest border, but is not yet positioned to fully quantify the impact these technologies have on its mission.

The pdf includes background information on border surveillance operations.