CONCORD, N.H. – Commuters, beware. The Democratic convention is coming.

Anyone traveling into Boston from Maine or New Hampshire or heading north out of Boston by bus after 7 p.m. can expect a longer trip in late July.

Travelers on Amtrak’s Downeaster can expect worse. Anyone flying in or out of Logan Airport also can expect inconveniences.

Blame for the possible traveling nightmare can be leveled at plans to close North Station. Interstate 93 will be closed after 7 p.m. from July 23 through July 30 because of heightened security.

It is the first political convention since the Sept. 11 terrorist attacks.

“It might make people so angry Massachusetts might go Republican,” General Manager Chris Andreasson of Vermont Transit Co. said of the traditionally Democratic Bay State.

Others have a different reaction.

“You’re looking at the luckiest guy in the world,” Concord Trailways driver Ernie Brochu said. “I’m on vacation that week.”

Many commuters apparently also are planning their vacations around the week. Jim Perkins of New London is one.

“Frankly, it sounds like everyone else is going to take the week off,” he said Thursday before boarding the bus to Boston. “I’m going to work from home that week.”

Paul Smith, a commuter who rides the Downeaster regularly into Boston, told the Portsmouth Herald he knows of about 20 commuters who plan to take a vacation during the week of the convention. Unfortunately, he must go to work.

Concord Trailways, Vermont Transit, C&J Trailways in Portsmouth and Northern New England Passenger Rail Authority, which oversees the Downeaster, haven’t finished their travel plans, but they are trying to make it as painless as possible for riders.

“We don’t have an exact answer on what we’re going to do,” said spokeswoman Patricia Douglas of the rail authority.

Bus officials have asked for waivers to allow them onto Interstate 93, while train officials have asked the Massachusetts Bay Transit Authority for permission to allow trains at the Oak Grove station in Malden, Mass., where passengers could catch the subway.

“We’re waiting to hear back from the T,” Douglas said.

“There are a lot of logistical issues,” and she mentioned a place at Oak Grove to store trains and make sure there are enough subway connections.

The train normally goes through Woburn and then to North Station. To reach Oak Grove, it would have to run on a different track that Douglas said probably carries commuter trains from Haverhill, Mass.

“We have to make sure there is room for everybody,” she said. “We’re hopeful we’ll be able to work out something.”

If not, riders can get off in Woburn and catch a bus, or get off in Haverhill and catch a commuter train and then a subway.

Douglas said the alternatives have been presented to train riders, and “they’re comfortable this is the best we can do.”

The Downeaster originates in Portland, Maine, and makes stops in Old Orchard Beach, Saco and Wells in Maine, and Dover, Durham and Exeter in New Hampshire. The eight daily round trips carry about 1,000 passengers.

C&J Trailways, which uses a section of Interstate 93 in and out of South Station, carries more than 1,000 people a day into Boston. Trailways President Jimmy Jalbert said that number might increase with train riders switching to the bus.

Any travel problems would arise only on buses out of Boston after 7 p.m. Jalbert said those buses could go through the Ted Williams Tunnel to the Route 1 north detour from Interstate 93. There could be delays because of possible increased traffic caused by others taking the same detour, he said.

Trips to and from the airport normally avoid Interstate 93, and would be no problem, he said.

Andreasson, of Vermont Transit, said the bulk of commuter traffic probably would be out of the city by 7 p.m.

“The big question is what kind of traffic” there will be throughout the day, he said. “We’ll just have to see what happens. It’s hard to predict.”