Decades later, the social and environmental costs of this arrangement have swollen. I asked the American Transportation Research Institute, which studies congestion using data from GPS trackers on freight trucks, to scrutinize Breezewood. The institute estimates that about 1.5 million trucks make the connection through Breezewood each year. The same methodology suggests that about 3.5 million passenger vehicles do, too.

But 80 percent of truck drivers do not pull over to refuel, eat or rest, the GPS data shows. The institute estimated that if ramps were built permitting drivers to avoid Breezewood, the trucking industry would save as much as 142,362 hours in driver time and $9 million in operating costs every year. Add to that the time and money savings for car drivers, to say nothing of eliminating the unnecessary carbon dioxide emissions from the fuel that both types of vehicles burn to travel the extra distance.

But if there were such a connection, millions of potential customers wouldn’t be funneled into Breezewood. Jim Bittner, who manages the Gateway Travel Plaza that offers fast food and gas in Breezewood, and whose family has owned businesses there for three generations, said he knew that Breezewood annoyed the people who don’t stop but that preserving it was important for this economically struggling region.

His family’s businesses alone employ about 200 people, he said, and his family has taken out millions of dollars in loans to upgrade facilities they cannot move elsewhere. He called the prospect of a bypass a “sword of Damocles” hanging over Breezewood.

“Any second, someone could come in and say, ‘Time’s up, the faucet is turned off, no more business is going to be coming off that road,’” Mr. Bittner said in an interview. “And then what do I tell the bank? How do I pay the loan off? How do I keep employing people? Where do they find jobs?”