LOS ANGELES — Once there was a little boy who rode Henry Huntington’s trolleys.

He was 4 when he first took a Yellow Car all by himself, along Vermont Avenue to nursery school. His mother handed him off to the motorman and said he was going to the end of the line.

Now that little boy is 88, and his mother and the trolleys are long gone.

He’s standing at a lectern at the San Marino, Calif., public library, clicking through black-and-white images on a screen.

Here’s a wooden Red Car trolley. Here are ladies, dressed to the nines, boarding a streetcar to shop downtown department stores.

Here’s the wide-open countryside that Red Car riders once viewed as they passed rural Compton on the way to Long Beach.

Even today, people want to hear about the trolleys, especially the Red Cars — how at their peak, they crisscrossed four counties on more than 1,000 miles of track, why they disappeared, what Los Angeles would be like if they were still running today.

It’s 7 p.m. on a weeknight, and every seat in the large room at the Crowell Public Library is taken. More than 20 people stand, leaning against the walls. And because maximum capacity has been reached, a dozen or so sit in the foyer outside, watching and listening through the open door.

His name is Jeff Arnett. He’s a retired financial executive, an enthusiastic historian and a longtime railway buff. He tells them all about how Huntington bought up land and grew his trolley system to take people to it.

He brings back to life a long-ago Los Angeles, when his father worked at Bullocks, where children learned manners in the tea room on Wilshire. In a city still being built, the sound of the streetcars carried, and from his bed he could hear them rumbling through the night.

On his solo trolley rides, he practiced reading, he says.

“On the streetcar was a sign I paid no attention to. It said, ‘Unnecessary conversation with the motorman is prohibited.’ And there was another one — a holdover from a little rougher era — that said, ‘Do not expectorate on the floor.’”

“I always used to wonder what that meant,” one woman replied. Many who have come are of a certain age. Quite a few rode the Red Cars themselves before the last remaining line shut down 52 years ago.

Bette Cook, 71, remembers coming into Los Angeles from San Bernardino for Madame Frey’s ballet class — and how riding the trolleys felt like “a big-city thing to do.” Joan Redford, 80, says she used to take the Red Car over the Cahuenga Pass from North Hollywood to Hollywood, to skate at the Polar Palace ice rink.

With Arnett as guide, they go back in time, to Red Car rides to the Catalina Steamer on the way to summer camp, to family holidays at Balboa when “father, if he spent the weekend with you, could catch the 7 o’clock train on Monday morning and be at 6th and Main by 8:20.”

Eventually, Arnett gets to the bit about trolleys fading out and buses rolling in and freeways being built. There are those in the crowd who want to hear him talk conspiracy or blame power brokers.

What’s gone is gone, but the tracks remain in their memories.