WASHINGTON, Sept. 22 (UPI) -- The U.S. government is looking into the lives of ordinary travelers to a far greater extent than most people know, say civil liberties advocates.

The government is building a surveillance database "largely without our awareness and without our consent," John Gilmore, a civil liberties activist in San Francisco told The Washington Post (NYSE:WPO) in a story published Saturday.

Through its Automated Targeting System, the government collects electronic records on the travel habits of Americans who fly, drive and take cruises, the Post reported.

The system, in use since the mid-1990s but greatly expanded in 2002, also screens data on the traveler's companions and personal items they carry, including books, the Post reported.

The data is meant to be stored for as long as 15 years as part of the Department of Homeland Security's effort to assess the security threat posed by all travelers, a DHS spokesman told The Post.