Every city has a pulse rate and you can feel it at the crosswalk.

Stand at one in New York and the pulse is fast and slightly angry. The light changes and the people go before it changes, they were already going, the light is a suggestion they have taken under advisement. Stand at one in Los Angeles and there's no pulse at all, you're the only person on the corner, and the button you pressed is connected to nothing, and a car goes by with someone in it looking at you like you're lost. Stand at one in San Francisco and it depends entirely on which hill you're on.

I didn't notice cities had pulses until I had lived in a few. The first one you live in is just "city." It's only when you move that you feel the tempo change, the way you only notice your own accent when you leave home.

Whose body

A nervous system implies a body. So whose is it.

I don't think it is the mayor's. I don't think it's the collective's, either, in the way people mean when they say "the people are the city." That's a nice thing to put on a plaque. The actual nervous system of a city, the thing that decides how fast the signals move, was mostly laid down by people who are dead. The width of the streets. Where the river was bridged. Whether the grid goes with the coast or against it. Some surveyor in 1850 with a chain and a hangover decided how long a block would be, and that decision is now the length of your stride, the length of a conversation between corners, the length of the pause before you cross.

So the city is somebody's nervous system, and the somebody is a committee of the dead, and you are living inside their reflexes.

The strange thing is that it works. You adapt within a week. Your walking speed changes. Your tolerance for eye contact changes. You start crossing when they cross, waiting when they wait, and by the second month you're one of the signals, a small electrical fact moving down a street that someone drew on paper before your great-grandparents were born.

The streetlights come on

There's a moment in every city I have loved, in the early evening, when the streetlights come on. Not all at once. In waves. You can see the timers are on slightly different clocks, so one block goes and then the next and then one behind you that you thought had already gone. It looks like a thought moving through something.

I used to sit on a fire escape and watch it. It felt like the only time the city let you see it thinking. All day it's too bright and too loud and you can't separate the signal from the noise, and then for ninety seconds at dusk the lights come on in sequence and you realize there's a sequence. Somebody wired it. Somebody chose the delay. The city has a wiring diagram and for a minute and a half you can read it.

The bus driver

If a city has a nervous system, the bus drivers are the part of it that's awake.

I mean this seriously. A driver on a route has driven that route a thousand times. She knows which stop the man with the walker gets on at and how long he takes, and she waits, and she does not announce that she's waiting. She knows the light at the bottom of the hill is short and she times it. She knows the block where kids run out from behind parked cars. Every one of these is a reflex the city has, and it's stored in her, and if you swapped her for a stranger tomorrow the route would be the same and the city would be, for a few weeks, slightly stupider.

I once rode a route to the end of the line and back, on purpose, for no reason, and watched the driver do this for two hours. Nobody thanked her. That isn't a complaint. Nobody thanks their spinal cord either. That's how you know it's working.

The Sunday morning problem

You can also tell a lot about a city by what it's like when nothing is happening.

A city on Sunday at seven in the morning has a resting heart rate, and that's where the personality is. Some cities are dead, really dead, no coffee, no birds, a feeling of a set after the crew has gone home. Some are quietly, thoroughly alive. Someone is hosing a sidewalk. Someone is arguing with a delivery driver in two languages. A bakery is doing whatever bakeries do at seven. The city isn't performing for anyone. It is just breathing.

That breathing is the real thing. Rush hour is the same everywhere, more or less, everyone going somewhere with a face on. It is the idle that differs. My theory, for what it's worth, is that when people say they love a city, what they love is its idle. The way it is when it isn't trying.

Being a signal

The part I didn't expect, when I moved to the city with the bad transit, was how much it would change my own tempo. I am a fast walker. I had always been a fast walker. Within a year I was walking slower, and I was walking slower because the city walked slower, and the city walked slower because of the hills and the fog and a thousand things nobody chose, and I had been absorbed into that without ever deciding to be.

That's what a nervous system does. It doesn't ask the neuron whether it wants to fire.

You can resent this. A lot of people do. They walk fast in slow cities and slow in fast ones and call it individuality. But I found I didn't mind. There was something restful in it. The city was making a decision I didn't have to make. My legs were on a schedule I didn't set, and the schedule was fine. It had been set by the dead, and the dead had thought about it, and they had thought about it for a long time.

The pulse at the crosswalk is theirs. You're just standing where they left the beat.