The New York subway system’s annual ridership is one and half billion, ranking it behind Tokyo, Moscow, and Seoul, but ahead of Mexico City, Paris, and London. It is quickest and cheapest way, short of walking, to get around the city. With more than 6,000 subway cars in service, trains can run a few minutes apart at peak times. Here three people are waiting for a Lexington Avenue local at 33rd Street. I waited for another train to rush through the background, creating a blur of silver. Since the destruction of the World Trade Center, an American flag appears on every NYC subway car. The flags are always kept illuminated, even when off duty.