The head of the world's 1.2 billion Catholics landed in the City of Brotherly Love after a short flight from New York, where he spent a whirlwind 36 hours that included an emotional visit to Ground Zero and mass at Madison Square Garden.
The 78-year-old Argentine pontiff is ending a historic visit to Cuba and the United States this weekend with a packed schedule in Philadelphia, including two appearances at the Festival of Families, an international gathering of Catholics.
The pontiff then got into the back seat of his modest Fiat, waving to the crowd as a band played welcoming music on the tarmac.
But at the sight of a child in a wheelchair close to the security barrier, he got out of the car and walked over to bless the child. He said a few words to the child's mother, who appeared moved almost to tears.
"We pray for you every day," said one sign held by a woman in her 50s who waited all night.
Philadelphia is under a security lockdown, with traffic banned downtown for the entire weekend and thousands of National Guardsmen in the streets.
Later today, Francis, the first pope from Latin America, is due to address immigrants at the city's historic Independence Hall before greeting huge crowds at the Festival of Families, a Catholic event that takes place every three years.
