Pope celebrates Mass at St. Patrick’s Cathedral

Still, Benedict has offered support to America's clergy during his visit.

He said priests who had done nothing wrong had been unfairly tarred by the crisis. More than 4,000 clergy have been accused of molesting minors in the U.S. since 1950. Abuse-related costs have surpassed $2 billion in that period, with much of the payouts in just the last six years. But most of the recent claims concern wrongdoing that occurred decades ago.

At the height of the scandal, which erupted in 2002 with the case of one predator in the Archdiocese of Boston, the shame was so intense that some priests took off their clergy collars before going out in public. Benedict compared their suffering to "Christ in his Passion."

However, morale has been improving as the intensity of the crisis has eased.

Seminary rectors say that their students are eager to show through their service to parishioners that the priesthood can still be a noble calling.

Yet Catholic clergy face other challenges beyond fallout from the abuse problem.

The priesthood has been shrinking for decades. More than 3,200 of the 18,600 U.S. parishes don't have resident priests, according to the Center for Research in the Apostolate at Georgetown University. More lay people than clergy work full-time in the churches.

The U.S. Conference of Catholic Bishops created a recruitment campaign called "Fishers of Men," that encourages priests to invite young men to consider entering the priesthood.

Dioceses have been hiring recruiters to travel overseas to find clergy candidates. The number of priests from other countries has grown so steadily that some seminaries are adding English classes, hiring accent reduction tutors and providing courses on American culture.

International recruitment is motivated partly by the exploding demand for Spanish speakers for the Hispanic immigrants filling the pews.

Leading a Mass in Nationals Park in Washington Thursday, Benedict asked the thousands of parishioners who crammed the stadium to "love your priests, and to affirm them in the excellent work that they do."

Later Saturday in New York, Benedict spoke to seminarians at a youth rally. On Sunday, the final day of his trip, he will visit ground zero and hold a Mass at Yankee Stadium.

After the Mass at St. Patrick's a roar went up from the crowd when the popemobile passed along Fifth Avenue, with people raising up their babies and others shooting pictures with cell phone cameras.

Daniela Rizzo brought her husband and their infant son from Connecticut.

"You can feel the energy," Rizzo said. "You can feel the faith."

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