Earlier in the day, workers lined up in their vehicles at the industrial park's secondary entrance early Monday morning and drove slowly into the center together, eyes straight ahead as they passed nearly 40 strikers marching around the building in drizzling rain.
"I've worked here since 1971. I know them all and I helped them all at one time. I just can't believe that they did it," said striker Linda Shank, holding a sign in one hand and an umbrella in the other.
The returning workers sorted, loaded and delivered about 3,000 packages and made several pickups in the area, which helped "stop the bleeding," Johnson said.
But the company was losing revenue and credibility, and complaints from local business owners and residents were mounting, he said.
UPS workers have been on strike since Aug. 4.
Chambersburg police watched the procession from a parking lot across the street and the center's managers stood outside the building, one videotaping the scene.
The strikers, not all of them local, didn't try to stop the workers from crossing the picket line.
Shank said they are "law-abiding people," and have no intention of turning violent.
"Contempt is the only thing you can feel," she said, adding that she needs a paycheck just as much as those who crossed the line.
The issue isn't about salaries. It's about labor practices, Shank said.
"I've worked my heart out for this company and then they treat you like this," she said.
Dressed in uniform, four UPS pilots represented by the Independent Pilots Association also joined the picket line in Chambersburg Monday morning.
"We're just down here supporting some of these people," said Capt. Tony Delduco.
"This is a fight for middle-class America," said pilot Andy Fetterolf.
He said many Americans eventually could be affected by a major issue of the strike: the spread of part-time employment.
Last week, some Chambersburg UPS workers met at a local bar to come up with a plan to cross the picket line, Shank and Johnson said.
Johnson said he informed them that there was plenty of work at the center but that the effort wouldn't be worth it if just two or three people returned to work.
The employees and their spouses apparently began calling others to join them, Johnson and Shank said.
According to Johnson, UPS workers crossed picket lines at other Pennsylvania centers in Lancaster, Harrisburg and State College on Monday.
By late Monday afternoon, no workers had crossed the picket line at the UPS center on East Oak Ridge Drive in Hagerstown, according to a local union official and strikers on the picket line.
A part-time sorter said that while he could sympathize with the Chambersburg workers, he feared their action would weaken the union's bargaining position.
"You've got to make a living, but I think it's a mistake because it makes progress go backward," said the man, who said he's held the second job at UPS for about a year.
Strikers face direct repercussions if they cross the line, said another part-time sorter, who said he's worked for UPS for about seven years.
The union can take your wages, fine you and suspend your union membership, he said.
The Teamster constitution both allows and encourages those sanctions when members violate their oath of loyalty to the union, said Linden Heavner, secretary/treasurer of Teamster Local 992.
Staff writer Kerry Lynn Fraley contributed to this story.