Cars began lining up before 7 a.m. to get into the parking lots at M&T Bank Stadium for the shuttle bus ride to Fort McHenry and the Blue Angels air show.
Yellow school buses stretched from Camden Yards to beyond the football stadium to handle the crowds, which are expected to fill the fort to capacity by 11 a.m.
The historic site holds about 25,000, but The Star-Spangled Sailabration is expected to draw 1 million people to Baltimore's Inner Harbor area by Tuesday. Elsewhere, several thousand people are expected to attend Gay Pride Parade activities in Mount Vernon, and the combination could mean congested traffic around downtown Saturday.
People are four-deep at the official Sailabration souvenir stand near the National Aquarium, buying T-shirts and white-topped captain's hats.
Lines to board ships stretch from the front of the Aquarium to the water's edge. People seemed unsure of which ship they were waiting for.
"It's the one from Argentina, right?" asked Angela Bottomsley of Arlington, Va. "I guess it really doesn't matter. It's tall."
Some visitors woke up before dawn to ensure they weren't shut out of the Fort McHenry festivities.
"I was like, 'I'm not going to brave the crowd,' but then I realized I may never get another chance," said Mary Edwards of Middle River.
City Department of Transportation staged 30 buses at the stadium for the 15-minute ride to the fort.
The air show featuring the Navy's precision flying team is scheduled for 2 p.m to 4 p.m. A patriotic show is to begin at 6:30 p.m., with fireworks to follow.
"You're not going to see the tall ships, the Blue Angels and Fort McHenry all at one time again," said David Meade of Westminster. "This is one you don't want to miss. You want to be the one talking about it not the one hearing about it."
William J. Pencek, Jr., executive director of the Maryland War of 1812 Bicentennial Commission, said the celebration has so far "exceeded our expectations."
He said that during the planning process, state officials led by Gov. Martin O'Malley, "wanted to move the needle in the way the nation and the world perceived us and how we perceived ourselves. So far, we're really good."
Along East Fort Avenue, police officers have taken up their posts at the corner of each block and firefighters at the Locust Point station are gathering in anticipation of large crowds lugging coolers, lawn chairs and blankets to the fort.
The city closed East Fort Avenue at Andre at 6 a.m. and parking is limited.
Back at the football stadium parking lot, Sonia Bunch of Silver Spring and her family waited to board a bus.
"I've got a pillow, blankets, chairs and food for a week," she said. "I think we're good to go."
Some people said they anticipated staying at the fort until after tonight's fireworks, but other folks on the shuttle line were already plotting their exit and a trip across the harbor to Fells Point.
"If you wait until the last rocket's red glare, you'll miss last call," said Charlie Gomez of Washington.