Mary Hayden Stehle, 5, and her 7-year-old brother, Will, watch the Christmas lights as their train passes through Ashland, Va., on their way home to Richmond from Washington. (Timothy C. Wright/For the Washington Post)

Five nights before Christmas, Mary Hayden Stehle is so deep into her Kindle jigsaw-puzzle game, she barely registers the racket of the train as it hurtles southward from Washington. Across the aisle, her brother, Will, sits on his grandfather’s lap, playing Minecraft. Neither child notices the dark forest outside, one seemingly filled with Wild Things.

But then, just beyond the woods, lights start to appear like fallen constellations. The youngsters set down their gadgets and drift over to the window.

“See the candy canes?” asks their mother, Michele Stehle.

The Northeast Regional pulls into the Ashland, Va., station, in the bull’s-eye center of town, and the Amtrak train becomes an insurmountable median on Railroad Avenue. Boarding passengers are privy to only one half of town (the section with the depot draped in white lights). Travelers already on board, however, can delight in the holiday display illuminating both sides of the iron rails.

“Oh, look! There’s a train made out of trash cans,” says Michele, pointing at a metal sculpture decorated with fir trimmings and ornaments designed by schoolchildren.

The locomotive bell rings. Onward to Richmond.

The sights flicker past. Reindeer prancing on lawns. Christmas trees playing peekaboo between half-drawn curtains. ­Diamond-bright bulbs trimming eaves and picket fences. ­Gem-colored lights dangling like Chanel necklaces on bare branches.

“Do you like the colored lights or the white lights?” Michele asks her children.

“The colored lights,” answers Mary Hayden, 5, after several minutes of speechless wonder.

“I like how the lights on the trees looked like they were flying,” adds Will, 7.

Oh, Christmas lights. They’re just plastic bulbs — yet they possess near-magical powers. They can transport you to the North Pole, or to a time predating Black Friday, or to a calm state guided by Zen Santa. We look at them and feel gooey and good, like a marshmallow floating in a cup of hot cocoa.

The good townspeople of Ashland, a Bedford Falls-like town about 18 miles north of Richmond, know this. And so they’ve bedecked their village streets with more than 100,000 sparkling lights for train travelers and freight crews to ooh and aah over.

“What we’ve done with the lights is to dial up what has always been here,” says writer Phyllis Theroux, who relocated from Washington more than 25 years ago. “Ashland really is a Christmas town.”

It’s even more of a railroad town. The first train arrived 180 years ago. Each day, more than 60 trains — 22 run by Amtrak, 40 by CSX — clatter up and down Ashland’s main drag. There’s no “wrong side of the tracks” here. Two tracks run through the main thoroughfare like a dry, rocky tributary. If a train pulls up just as you were planning to cross the road, you’d better take a seat — this could take a few minutes.

“The train is such an integral part of our daily life,” says Dan Bartges, an artist and Ashland Main Street Association board member. “We wanted to make the entire town twinkle for the train crews and passengers.”

Through Jan. 3, railway passengers heading home for the holidays — or simply slogging through their daily commute — will coast through the mile-long Light Up the Track event. As for the blurring special effects, you can thank the train engineers. When you’re moving at up to 35 mph, the lights do appear to sprout wings.

The dazzling illumination beams from shops, houses and yards paralleling the track. Most of the decor is traditional: white lights, red velvet bows, wreaths, electric candlesticks, a jigging snowman.

“It is so welcoming and nostalgic,” says Ashland resident Stephanie Werner, the maternal grandmother of the Stehle children.

Some locals, however, have apparently drunk from the whimsy punch. Yes, that is a carved-wood tiki head wearing a sweatband of red bulbs.

The lights surprise most travelers, who are typically staring into phones, computers or closed eyelids. Unless otherwise informed, they’re not prepared for the diversion created on their behalf.

“If I knew ahead of time, I would go ‘Ooh’ and ‘Aah,’ ” says Desiree Sisitka of Hampton, Va., “like I always do when I see lights.”

On the trip up to Washington that Monday morning, Sisitka had mentioned to her husband that she hoped the train would pass through towns decked out for Christmas. Unfortunately, the couple were traveling during daylight hours. Also working against them: The scenery along the northbound route is mainly forest, farmland and the backsides of towns. But they were returning in the dark and stopping in Ashland — so maybe, just maybe.

On occasion, the conductor announces the upcoming show. The staff might also share wisdom from its repeat rides through the display.

“They’re on both sides,” an employee informs us at Washington’s Union Station about the lights, “but I think this side has nicer ones.” To clarify, “this side” means left (if you’re heading south).

A staff member at the Richmond Staples Mill Road station advises us, now headed north, to sit in the cafe car. He demonstrates how you can easily swivel your head to see out both picture windows framing the festive scenery. Suddenly, a cellphone rings, releasing “Jingle Bells” into the air. The mood is set.

A resident draped the front yard trees with colored lights — all the better to be seen from a passing train. (Timothy C. Wright/For the Washington Post)

Ashland’s Victorian houses offer a burst of illumination for the holiday travelers. (Timothy C. Wright/For the Washington Post)

For passengers on the southbound train, the display starts with Randolph-Macon College, which demonstrates its merriment by wrapping white lights around lamp posts. Downtown follows. Then a row of Victorian houses. A few dark patches intervene before a stunning residence with a wide lawn bursts onto the scene like the Noel version of a Fourth of July fireworks finale.

“I want to see it by foot,” Sam Westrick, a PhD student in Pittsburgh going to visit his parents in Mechanicsville, says after the show.

The Sisitkas spend the final leg of the journey tossing out Santa-sanctioned ideas. Perhaps Amtrak could serve spiked eggnog, hand out candy canes and play Christmas carols over the P.A. Maybe the staff could don holiday gear. And how delightful if the train could park in Ashland for 15 minutes, so passengers could disembark and experience the lights up close.

On this evening, however, the train has other plans and plunges back into the darkness. But Ashland’s lights continue to burn bright, ready to greet the next load of passengers. Because without the decorations, it’s just another night on the tracks.