At 6 o’clock on a weekday evening in early July, Union Square is most alive. The small, oval park at its center, three acres of green nestled between four broad streets, throbs with music and conversation, with voices rising and swelling to join the steady drone of traffic on all sides. You see children swinging under their parents’ eye in small playgrounds on the park’s northern edge; at the southern end you pick your way carefully through a swarm of a couple hundred young men and women who are milling around the wide, shallow stone steps leading up to the park’s main entrance. Tourists browse the T-shirt and art vendors’ tables while other shoppers stop at the Greenmarket on their way home, and every fifth person in the crowd is making a call or reading a text message on their cell phone. The crowd skews young, mostly under thirty-five, their faces are mainly white but also black and brown and several shades of tan, and you hear a girl ask, “Where are you? Are you in front?” in Japanese on her phone. Next to the subway entrance a lone political demonstrator uses a portable loudspeaker to make a speech against the U.S. president; nearby, under a statue of George Washington on horseback, two New York City police officers, also on horseback, interrupt their early evening patrol to chat with a park cleaner in a bright red uniform and a private security guard in navy pants and a matching cap. So many people are sitting on green wooden benches under the trees that you can hardly find two seats together. Most of the occupants are watching the parade of passersby; some are listening through earbuds to portable music players, others read a book, and one or two doze. In the fenced-in dog run, pets frisk about while their owners laugh and talk. A trio of young musicians sits on benches in the middle of the park, setting up a cello and two violins for an informal outdoor rehearsal.