It’s not possible to live near train tracks without trains taking root inside of you. Until I was 6, my family lived in Evanston, a couple of blocks from an overpass for the Yellow Line, the five-mile vestigial tail of the L system. I dreamed of the Yellow Line regularly. I dreamed of standing alongside the tracks, or in the hushed greenery beneath that overpass. Let’s just skip whatever Freudian interpretations this evokes. My therapist suggested that my dreams represented an urge to escape. I can buy that. The Yellow Line, in its tiny peculiarity, feels completely removed from the city. It feels pastoral, atavistic. It feels like a place of refuge.

The Yellow Line train is two cars long. From the Howard terminal, it pushes past the tangle of the train yard, heading north as it plunges partway into the ground, between low green embankments running along Case Street in Evanston. Soon the train climbs back upward, past the Jewish Reconstructionist Congregation (where I half-assed my bar mitzvah) and Mount Trashmore in James Park (where I half-assed my soccer practice) and on toward Skokie, passing another train yard, some open fields, and a car dealership (where I made a half-assed attempt at adulthood by buying a Subaru). Three stops: Howard, Oakton, Dempster. Then it’s done.

In the prewar years, the rail line was part of the North Shore and Milwaukee Railroad and was known prosaically as the Niles Center Branch. It ran all the way into downtown Chicago. For various 20th-century reasons, the line was discontinued and eventually repurposed by the CTA as the Skokie Swift. It bore that name until 1993, when the CTA decided that colors made better names for train lines than, well, names. (But let’s be honest: The Yellow Line sounds like a demarcation of moderate geopolitical danger along the Adriatic after World War II.) For longtime riders, it is still the Skokie Swift.

The Skokie Swift, the Yellow Line — the little engine that could and still can — is all but invisible to most Chicagoans. Lost at the top of an L map, the filament of yellow juts out like an antenna, probing cautiously into the distance. At the Andersonville branch of Transit Tees, a shop specializing in CTA-related souvenirs, the guys at the counter acknowledge that Yellow Line merchandise isn’t in high demand. For people who know the train, one of them said, it’s more like an inside joke. Among the dozens of magnets bearing the names of L stops, I found only three labeled with Yellow Line stations, which felt pretty unfair until I remembered: That was it. That was the Yellow Line. Three magnets. They had the entire route.

For me, every ride on every mode of public transportation is bracketed by a why. Namely, why are these other passengers here? On the Yellow Line, the why is amplified. Why is this train even here? Why is this three-stop curio that can’t get you directly into the city or even to the mall or the county courthouse even running? The Yellow Line had around 673,000 riders in the first nine months of 2018. By comparison, the Red Line averaged 1.5 million passengers a week. A very cursory survey of other major rapid transit systems in the United States suggests the Yellow Line is the shortest train line in the country by stops and length. (OK, there are a few lines in New York City’s subway, like the 42nd Street Shuttle, that are shorter, but since I’m the judge here, I’m disqualifying them because they’re shuttles.)

On a recent weekday morning, the rush-hour crowd waiting for a Skokie-bound train was surprisingly thick. False density: The platform is only as long as the train. Standing among the commuters, I felt the familiar why rise up. Who am I to look into the motives of strangers? Still, indulging the impulse seemed harmless enough.

There were a handful of high school kids headed to class, clumped in a glum pack. They told me they went to Notre Dame College Prep in Niles. An older man, probably in his 60s, wearing a Bulls knit cap, said he was coming home from work. Night shift, I presumed. He’d rather not give his name or his employer, he said. I asked what he thought of the Yellow Line. He wasn’t sure what I meant. I tried narrowing the question and breaking it in two: What’s it like riding it compared with other lines? Why does he think it’s still here? By then we were on the train. He looked around and gave a laugh, as if I’d missed something extremely obvious. “Yeah, it’s small. But people need it, right? People go to work, to school, you see.” He seemed to be growing impatient. “I think most people would think, I’m glad it’s here.”

I suppose I am, too. And yet those few minutes spent aboard the Yellow Line from beginning to end were reminders for me of discarded plans, old hopes, the unrealized and the unfinished. “Our lives glimpsed like back gardens,” Anne Michaels wrote in a collection of poetic meditations about trains called Railtracks, “with a washing line — a persistent optimism — as the train draws out.”

Trains themselves are persistent, melancholy, fleeting: ghosts with important business someplace else. Keep your windows open late on a warm night and you might hear a far-off caution, doors closing. The chime doesn’t signify departure in my mind, but rather the entire city momentarily collapsing into a single mechanical sound. When I was in my 30s, I lived in Andersonville, bedroom window facing east, where I heard those late-night chimes from Bryn Mawr. Then I bought a house on Ravenswood Avenue, beside the Metra tracks my father took to work for decades. The first home seemed random, the second seemed fated.

I don’t dream of the Yellow Line anymore — by midlife, the fantasy of escape is no longer sublimated. But my son, who inherited my thing for trains, is fond of the Yellow Line. “Why?” I asked him once. He thought on it and finally said, “It’s just cool.”