Not far into the chilly dimness of the Big Savage Tunnel, I started to feel panicky: The archway of proverbial light at the end was not getting larger, as if I were not getting nearer. As much as I pedaled, it seemed I wasn’t progressing.

The illusion passed, and after a few minutes my wife, Susan, and I emerged into the hot sunlight of southwestern Pennsylvania. But that tells you how long the tunnel is — about two-thirds of a mile — and it’s just one of the stunning features along the Great Allegheny Passage bicycle trail from Cumberland, Md., to Pittsburgh.

The pandemic has closed so many travel options, but not this one, which has been on my bucket list for ages. The 150-mile route picks up where the Chesapeake & Ohio Canal towpath from Georgetown to Cumberland ends. It thrills me to know that our land is threaded with forgotten corridors left over from antique transport modes — mule-pulled canalboats, coal-fired locomotives — that still connect major metropolitan areas. Susan and I were familiar with the towpath, but the Great Allegheny Passage was unknown to us, almost exotic sounding: “passage” through what? This three-day ride in late August would be a test of how far from the cares of 2020 you can get on a quick local vacation.

We found the medallion marking Mile 0 of the GAP, as the passage is known, embedded in the pavement of the little plaza that serves as the transition from the end of the towpath. It must be a magical keyhole, because pedaling off the sidewalks of Cumberland and onto the trail felt like vanishing into an alternate dimension where we were euphorically alone and sprung free.

The route hugged a creek through a deep wooded gorge and for a time ran parallel to the Western Maryland Scenic Railroad. As the miles rolled behind us we listened to the cicadas and the crackle of crushed limestone beneath our tires on the hard-packed trail. I was riding an ancient Trek that I had used in college. Susan was astride a commuter bike that she got when she was headed back to work not long after the birth of our first daughter, nearly 22 years ago.

Hypnotized by the rhythm of pedaling, one of the first things we talked about was our dreams. Not our dreams for the fraught future, but our dreams from last night and the night before. We pondered the random people from our past who appeared in them, and we speculated on whether we existed in their dreams. I couldn’t remember the last time we’d had one of these aimless, spacey conversations we used to have so often. “It reaffirms how fun it is to be just the two of us,” Susan said at one point.

We had both spent the previous days focused on coverage of the 57th anniversary march to commemorate the 1963 March on Washington, a continuation of a summer of protests for racial justice, and now, at Mile 20, the passage was taking us from Maryland into Pennsylvania across the Mason-Dixon Line, the traditional border between the North and South. It’s marked by stones inlaid diagonally across the trail. A few miles earlier, on a rusted railroad signal post, I had seen scrawled in chalk the name of George Floyd, who was killed in police custody in Minneapolis, well north of the Mason-Dixon. As I crossed over, I thought about how some borders have lost their meaning in 2020.

The Eastern Continental Divide, at Mile 23, seemed equally unremarkable at first. A culvert marked our passage over the geographic divide between the watersheds of the Atlantic Seaboard and the Gulf of Mexico. I shrugged and spat on either side so a little of my DNA might make it to both the Chesapeake Bay and the Gulf of Mexico. Only as we continued pedaling did we notice: The going had become subtly easier. The trail had been barely perceptibly uphill from Cumberland. But from here on, the passage to Pittsburgh would be slightly downhill. With no extra effort, our pace increased from 7.5 mph to 10. I felt an inexplicably profound satisfaction in realizing that, even though technology has vanquished topography, on my bicycle, a force so elemental still counted.

We stopped for food breaks and lodging in river hamlets and railroad towns where charming bed-and-breakfasts, brewpubs and bicycle shops are just hanging on through the pandemic. Some of the food options were gourmet, but the best dinner after a long day of riding — a Sunday, when the restaurants were closed — was actually a gas station pizza that we split, along with a few Fat Tire beers, chosen for the bicycle printed on their labels.

The trail continued along another old railroad right of way, which, in 1912, opened the most efficient route for freight to travel from Pittsburgh’s factories to the East Coast. This corridor had been carved in record time by laborers who were African American and immigrants from Ireland, Italy and Mexico. We felt a gratitude toward them because of our reliance on the monuments they left behind: the incredible tunnels that pierced the mountains and the panoramic bridges and viaducts that spanned swift-flowing creeks and lush cornfields.

Around Mile 93 I spotted what looked like little caves in the woods on the side of the trail. But upon closer inspection I saw that they were the mouths of disused coke ovens, where the high-quality coal mined nearby was baked into fuel for the steel mills of Pittsburgh. Now trees had grown around the abandoned brick kilns, and brambles and spiderwebs camouflaged their openings. We paused at trailside memorials to mine disasters — 239 miners killed in an explosion in 1907; nearly two dozen blown up or entombed alive in 1901. These calamities occurred just off what is now the bike path, but the forest has erased most traces of that way of life and death, except for a few shiny black coal seams that still beckon from rock formations beside the trail, and a red waterfall of acid runoff from one old mine that stains logs and stones the color of cayenne pepper.

What couldn’t be erased was how the pandemic has hammered business at the retail plazas planted where the mighty mills that helped win World War II used to be. We pedaled across empty parking lots, admiring vestiges of steel glory preserved like sphinxes in a postindustrial desert: a massive gantry crane marooned between a Courtyard by Marriott and a Hampton Inn; a dozen towering brick venting stacks standing sentinel over an AMC movie theater and a LongHorn Steakhouse.

Eventually, from the deck of the Hot Metal Bridge over the Monongahela River, we could appreciate the skyline of a city that no longer depends on coal or steel. We then cruised to Point State Park, where the Ohio River begins, and where another medallion embedded in the pavement told us we had reached the end of our passage. It was an abrupt return to 2020. Cars, crowds, the threat of the coronavirus and raw impatience seemed everywhere. “You’re not supposed to stop there!” snarled an urban biker when I paused to take a picture. I pulled my bandanna over my face for the first time in three days of riding.

Susan and I looked at each other. Yes, we were back where we started. But what a long way we had traveled in the meantime — and much farther than the 150 miles between the two medallions. A history of America had unspooled for us along those miles, both tragic and inspiring. I felt more hope in my own endurance, and in the nation’s, than I did three days before. The darkest of tunnels comes to an end, I knew, if you just keep pedaling.

David Montgomery is a staff writer for the magazine.