How bad is the 4?

The 4, the green express that carries the east side

The 4 is the express half of the Lexington Avenue line, the busiest subway trunk in North America, and it runs the way a flagship should. It begins at Woodlawn in the northern Bronx, drops down the Jerome Avenue corridor, runs express beneath Manhattan's east side, and crosses under the East River to finish in Brooklyn at Crown Heights–Utica Avenue. Its green roundel is the one you follow from Yankee Stadium to Midtown to the Brooklyn Bridge, all without touching a local track in Manhattan.

Weekday rush is when the 4 shows off, running express and fast with a train every few minutes. Late at night it humbles itself and makes the local stops on Lexington Avenue, so a midnight 4 spends its evening doing the 6's job while wearing a 4 on its front. That shift surprises visitors and mildly irritates regulars. Once you know it, though, it is useful: a late night 4 still gets you home, just at a lower altitude of ambition.

The neighborhoods on the route cover an astonishing range. In the Bronx: Woodlawn, Norwood, the Grand Concourse, and the stadium district around 161st Street. In Manhattan: Harlem at 125th Street, then the Upper East Side with its museums and hospitals, Grand Central, Union Square, and the civic core around City Hall. In Brooklyn: Borough Hall, the Barclays Center, and the long run out to Crown Heights. It is the line that carries tourists to the bridge and residents to work in the same crowded car.

Grand Central is the pressure point. The platform is tight, the crowds are relentless, and the transfer between levels can feel like a queue at a stadium gate. Add the shuttle and the 7 and you have one of the busiest interchanges on earth, which means a small delay becomes a large one quickly. Riders learn which end of the train to board for the fastest exit, and they guard that knowledge the way they guard a good parking spot.

Up in the Bronx the 4 is the only express for a long stretch of Jerome Avenue, and it is the train that gets Yankees fans to the ballpark and back. On game nights the cars fill with caps and jerseys and the whole line takes on a different mood. Few routes flip so completely between commuter silence and event noise. It is also, on those nights, the fastest way out of the Bronx after the last out, which is worth something when you are standing in a crowd of forty thousand.

The Brooklyn crossing uses the Joralemon Street Tunnel, one of the earliest tubes dug beneath the East River, a piece of engineering that was genuinely daring when it was built. Trains drop under the water and come up under Borough Hall, and the whole thing takes less than a minute. Nobody on board looks up for it. That is the strange fate of great infrastructure: it becomes so ordinary that only the people who built it and the people who maintain it remember it was ever hard.

What the 4 is good at is raw speed on the east side and coverage that links the Bronx, Manhattan, and Brooklyn in one seat. Comfort is another matter entirely. The cars are jammed, the noise never stops, the tunnels get genuinely hot, in the system, and it almost never gives you a window worth looking out of. East Side residents, Bronx commuters, and Brooklyn riders depend on it anyway, because the alternative is a bus, and nobody is choosing the bus.

Union Square and City Hall are where the 4 earns its weekday keep. From Union Square it leaps the long gap down to the civic center, and riders who work downtown treat that single express hop as the reason they chose the east side at all. It is not a scenic route. You will not see the skyline from the tunnel, and the platforms downtown are dim and hot. But the 4 turns a long commute into a short one, and for a train that crowded, that is the entire sales pitch.