The U.S. government is collecting electronic records on the travel habits of millions of Americans who fly, drive or take cruises abroad, retaining data on the persons with whom they travel or plan to stay, the personal items they carry during their journeys, and even the books that travelers have carried, according to documents obtained by a group of civil liberties advocates and statements by government officials. The personal travel records are 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 entering the country. Officials say the records, which are analyzed by the department’s Automated Targeting System, help border officials distinguish potential terrorists from innocent people entering the country. But new details about the information being retained suggest that the government is monitoring the personal habits of travelers more closely than it has previously acknowledged. The details were learned when a group of activists requested copies of official records on their own travel. Those records included a description of a book on marijuana that one of them carried and small flashlights bearing the symbol of a marijuana leaf. […]