The Greyhound bus company, the nation’s largest intercity bus company, has threatened to fire employees who sell bus tickets to undocumented immigrants. The company’s so-called “Transportation of Illegal Aliens” policy warns Greyhound’s customer service employees to beware of people in large groups, moving in single file and traveling with little or no luggage. It says other telltale signs include people “trying to hide or stay out of plain view” or large groups led by a “guide” who holds everyone’s tickets. Greyhound also says immigrant smugglers give themselves away by calling bus stations to ask if immigration authorities are present, and by loitering, repeatedly buying large numbers of tickets for other people and using phrases like, “These guys just crossed the line,” “my cargo,” and “I’ve got to move my people.” The policy warns that failure to comply could result in the employee’s firing and possibly arrest. The policy was largely unknown outside the company until La Opinion, a Spanish-language newspaper in Los Angeles, reported on it earlier this month.