"Civilian patrols along the international border have existed in a wide variety of forms for at least a hundred and fifty years. Over the past fifteen years, civilian border patrol groups appear to have proliferated along the U.S.-Mexico border, partly due to the increasing numbers of aliens entering the country illegally. In the spring of 2005, attention focused on these civilian patrols, when the 'Minuteman Project' mobilized hundreds of volunteers along the Arizona-Mexico border to observe and report the movement of illegal aliens to the U.S. Border Patrol. Although some participants were armed, Minutemen volunteers were instructed not to engage in hostile confrontations with any illegal alien. Organizers of the Minuteman Project have expanded the Project to the other southwestern border states and Canada and have split the mission into a border defense corps and an internal vigilance operation that monitors businesses and government. A new nationwide Minuteman Project began in April 2006."
CRS Report for Congress, RL33353