PITTSBURGH -- Pope Benedict XVI arrived at Andrews Air Force Base near Washington, D.C., for his first official visit to the United States on Tuesday, and was greeted upon landing by President George W. Bush and first lady Laura Bush.

After greeting U.S. church officials and dignitaries, a motorcade conveyed the pope and president's entourage to the Vatican's embassy.

The pope's six-day visit to Washington and New York is scheduled to be filled with high-profile events.

A crowd of up to 12,000, larger than the gathering for Queen Elizabeth II, is expected at the White House Wednesday to greet Benedict on his 81st birthday.

During the pope's stay, he will meet with Bush at the White House, speak at the United Nations, visit Ground Zero in New York City and hold two stadium masses.

Some local high school students will attend mass this week with the pope. About 250 people from the Pittsburgh Diocese will travel by bus to hear the pope's message in Washington, D.C. They are joining thousands of others from throughout the country. They will attend Thursday's mass at Nationals Park in Washington.

Ringgold High School student Maura Rodgers said, "No matter how low your SAT score or how high or how often you participate in sports, there's never a denial letter to the Catholic Church. There you're accepted all along. No matter what, there's always forgiveness."

Mike Kaufman, from Upper St. Clair High School, said, "To feel that energy, to feel that, the grace of the Holy Spirit that's there it's, it's revitalizing. It gives you so much joy and strength so that when you come back to your regular lives."