Workers complained they had not been given the chance to vote on their company's proposed contract.
In the last vote they took less than two weeks ago, 65 percent of Local 992 agreed to strike if necessary, said union Business Manager Bill Armes. Nationwide, the same vote was 95 percent.
"They should really have more confidence in their international leadership," Armes said.
Workers said they feel like pawns in the dispute between the Teamsters and UPS.
Teamsters say the strike is about increased wages and safety standards, an end to subcontracting and more full-time jobs.
But some workers suspect the heart of the dispute is over who controls the employee pension fund - the Teamsters or the company.
"They're playing with people's livelihoods here. Right now I'm embarrassed about the union," said Zachary Morse, 37, of Hagerstown. "My motto is this: I don't need a godfather. I need a job."
Morse also feels bad for his customers and everyone who is being inconvenienced by the strike.
Many drivers said they didn't expect the dispute to go this far.
Local UPS workers are to receive $55 a week strike pay, quite a difference from their $19.95-an-hour full-time pay.
Bob Hassler, 47, of Fayetteville, Pa., said he saw management's proposal last week and got his first good look at the union's proposal on Monday.
"To me, the difference between the two is not worth being on the street for. Now I'm going to see my savings virtually go out the window," said Hassler, who is putting a daughter through college.
"I don't want to see it drag out. It's a hardship on everybody," said Art Lucas of Big Pool, one of only a few employees who remembers a 1976 strike that lasted 89 days.
Bill Seltzer, 47, of Hagerstown, said the company appeared to be offering one of the best contracts he has seen in 25 years.
"I think we're being held back by our union," he said.
Drivers worry that UPS will lose permanent business because of the strike.
Anticipating problems with UPS deliveries, at least one area mail-order distribution center switched over to the U.S. Postal Service last week.
So far, there have been no complaints, said Steve Kalsch, director of distribution operations at Norm Thompson Inc. of Kearneysville, W.Va.
"I think it's going to make a lot of people rethink," Kalsch said.
The Hagerstown Post Office was able to handle the increased load of packages on Monday, said Postmaster Robert Gingell.
Federal Express could not be reached for comment.
"Everybody's trying to get a piece of the action" said Mike Kiley, owner of Mail Boxes Etc. in Hagerstown.
At the Hagerstown UPS center, packages were still moving - barely.
A handful of workers on the picket line had a good-natured laughed seeing their managers driving the trademark brown package trucks. One manager forgot to turn off the truck's turn-signal.
Passing Roadway truck drivers, who also are represented by the Teamsters, honked in support of the picketers.
Silver trailers, which would normally be on the road, were lined up end-to-end, creating a barrier between the center and the picket line.
At the Chambersburg center on Industrial Drive, about seven people were standing in different spots around the building at 2 p.m., all carrying signs.
There and in Hagerstown, they were taking turns in three-hour shifts.
About 100 people work at the center, including 40 drivers and the rest part-time employees, according to one of the picketers.
Some of their signs read: "Teamsters Strike UPS Bad Faith Bargaining" and "Teamsters Local 992 On Strike."
Staff Writer Lisa Graybeal contributed to this story.