As the motorcade approached, people all along the route pressed in for a closer look.
Waving from his white, bulletproof Mercedes-Benz, surrounded by a squad of jogging Secret Service agents, the pope rolled down Pratt Street to cheers and cries of "We love you, John Paul."
Horaly Joya waited 15 hours on Pratt Street for a glimpse. Despite a front-row seat just behind the orange plastic crowd-control fence, a glimpse was about all she got.
The pope's motorcade covered the Pratt Street leg in less than five minutes.
Still, Ms. Joya was glad she came.
"We came here to honor him," she said. "He's the most important person here on Earth."
People started lining the streets early, setting up folding chairs and spreading out blankets along the route from Camden Yards along Pratt Street, up Light Street to East Baltimore Street, over to Charles and up to Saratoga Street.
At most places along the route, there was plenty of room to see the pope and the parade.
As he celebrated Mass at Camden Yards, thousands of people flocked to the Inner Harbor to watch the Eucharist on three JumboTron television monitors. When the pontiff left the stadium around 1:50 p.m., the crowds started to swell at the corner of Pratt and Light streets.
In some places, people were standing 30 to 40 deep. One of the busiest places was the plaza of the World Trade Center.
After a morning of anticipation, the crowd suddenly became quiet after the Mass, waiting to hear the rumble of the approaching motorcade.
"Here he comes," a father called to his children, scooping them up in his arms so they could see.
"Oh, my God, it's him," a woman yelled.
A man waved a sign that read, "Welcome Hon."
Forty trumpeters standing on the steps of the plaza started to play the opening theme from "Also Sprach Zarathustra," well known as the theme from "2001: A Space Odyssey."
Fifteen police Harley-Davidson motorcycles turned the corner at Pratt and Light, followed by a long line of police cars, vans and black Chevy Blazers carrying dozens of officers and Secret Service agents.
The popemobile rolled by, prompting dozens of people to start running up the plaza along Light Street, chasing the procession into the heart of downtown Baltimore.
Twelve more police motorcycles rumbled past and the marching and music began.
It took nearly an hour for the 2,700 participants representing nearly 70 groups to stroll by, twice as long as organizers had expected.
That didn't seem to bother the spectators.
"It gives you such a wonderful feeling inside," said Vivian May of Owings Mills as the parade began.
Music and marchers moved past the crowd. The Marching Terrapins. The Mexicano Association. The Calvert Hall Marching Band. Club Dominicano. Ojczyzna and Kalina Polish Folk Dance Ensembles. Parishioners from around the state. The Baltimore City Marching Band.
Wayne and Alice Wideman of St. Louis followed the pope to New York and then to Baltimore.
How did the two historic visits compare?
"This is much better," said Mr. Wideman, who was wearing an American flag sweater and an orange Niagara Falls baseball cap as he stood on Light Street.
"This is a beautiful city. And the people are really nice here."