In Washington County, trucks make up 9 percent of the traffic on Interstate 81, but that figure can be misleading. Officials say the percentage is lower, not because fewer trucks are traveling I-81 along that stretch, but because overall, traffic is heavier in that area.
Commuters may curse the lumbering beasts for clogging the highways, but others say the trucks are a sign of prosperity.
"They should all be banned," said Jim Aden, 52, who commutes to Washington, D.C., from Waynesboro, Pa.
As if Monday mornings weren't hard enough, Aden says, there seem to be more trucks traveling at that time of day.
"It's like one truck after another. At times, it's very nerve-wracking," he said.
Trucks tend to control the flow of traffic, whether they are traveling at breakneck speed or going agonizingly slow up a mountain, he said.
"They hog all the lanes. It adds onto your commute," said John Hanley, who travels from Frederick, Md., to Herndon, Va., via U.S. 15.
On the other hand, the interstates play a role in the livelihoods of many area families.
Dozens of companies - including Roadway Express, Food Lion, Federal Express, Georgia Pacific and D.M. Bowman Inc. - rely on the interstates to move products.
Last year, more than 3,000 jobs in Washington County were tied to transportation, communications or utilities. That was 6.6 percent of private sector jobs, according to the Department of Labor Licensing and Regulation.
Eli Hall, general manager of Travel Port in Greencastle, Pa., said he has noticed more traffic on Interstate 81 near Chambersburg, Pa.
"Chambersburg has grown. Just look there on Orchard Drive. There's a lot of trucks going in there that weren't before," Hall said.
More trucks mean more wear on roads and increased risks for serious accidents involving hazardous materials, officials said.
"We've been fortunate we haven't seen a drastic increase in improperly stored materials," said John Bentley, deputy chief of the Washington County Hazardous Incident Response Team.
Although there may be more trucks than ever on the road, the trucks are in better working condition, said Lt. Bill Bernard, assistant commander of the Maryland State Police commercial vehicle enforcement division.
"The trucking industry has improved the quality of the equipment out there," Bernard said.
When police began an inspection program in 1985, 60 percent of the trucks checked had to be pulled out of service for violations.
In 1995, the number had dropped to 36 percent, he said.
Accidents involving tractor-trailers are more likely to result in injuries and to tie up traffic for longer periods, thus throwing them into the limelight.
But Bernard said truck drivers most often are not to blame.
"In most cases, it's the error of the car," he said.
Despite the general increase in truck traffic, the Hancock Truck Stop has not seen more business, said Manager Judie Pearce.
Pearce blames a combination of a winter-weather slowdown and an Interstate 70 sign that town officials recently installed.
The intent of the sign was to discourage trucks from driving downtown, but Pearce believes that it causes truckers to bypass the restaurant, which is right off the interstate.