Possible Clues:

• 1959 folk hit with the line "Charlie couldn't get off of that train"
• Commuter train org. in many cities
• IRT operator
• Where Charlie 'may ride forever,' in a 1959 hit
• Where Charlie "may ride forever," in a 1959 hit
• NYC bus operator
• Letters on an N.Y.C. fare card
• N.Y.C. subway inits
• Org. for commuters in many big cities
• Kingston Trio hit that inspired the CharlieCard for Boston commuters