One year after a deadly tornado devastated their city, President Barack Obama praised the residents of Joplin, Mo., for a spirit of perseverance and resiliency that he said could serve as a model for a nation still grinding its way through tough economic times.

Obama delivered a high school commencement address a day before the anniversary of the twister that killed 161 people. Declaring that they had "already defied the odds," he urged the graduating seniors of Joplin High School to hold close the lessons they learned in overcoming adversity as they enter the next phase of their lives.

"You are from Joplin. And you are from America," Obama said. "You will not be defined by the difficulties you face, but how you respond — with strength, and grace, and a commitment to others."

Obama jetted to Joplin immediately after wrapping up the national security-focused NATO conference in Chicago, the second international summit the president hosted over the past four days. He joined school leaders and local officials on stage in the gymnasium of a local college, listening to student speeches, choral performances and the school cheer.

The Joplin twister was the country's deadliest single tornado in six decades. Beyond the dead, hundreds more were injured and thousands of buildings were destroyed, including Joplin High. Five other Joplin schools were also destroyed, with four more among the damaged structures.

The twister arrived hours after last year's high school graduation. Will Norton, a member of the 2011 graduating class, was killed, as was Lantz Hare, who would have graduated next year.

"You've learned at a younger age than most that you can't always predict what life has in store," Obama said. "No matter how we might try to avoid it, life surely can bring some heartache. And life involves struggle. And at some point, life will bring loss."

Obama traveled to Joplin in the days after the tornado struck, meeting with residents and viewing the devastation. On Monday, he praised the city's residents for the determination they have shown over the past year in rebuilding their homes and businesses, as well as those from across the country and the world who stepped in to help.

Obama urged the graduates to never forget the kindness and generosity bestowed upon their town in the days after the tornado.

"There are so many good people in the world," he said. "There is such a decency, a bigness of spirit, in this country of ours. So class of 2012, you've got to remember that."

That same spirit, Obama said, is needed to help rebuild America after nearly four years of economic strife.

"America only succeeds if we all pitch in and pull together — and I'm counting on you to be leaders in that effort," Obama said.

Though Joplin's schools were destroyed, officials had vowed to start this school year on time. They turned a vacant big-box retail store at the city's only mall into a temporary high school for juniors and seniors, with freshmen and 10th-graders at another location across town. A middle school relocated to an industrial park warehouse.

On Tuesday, the Joplin school system will symbolically break ground at three new schools being built to replace those lost last year, including a new high school expected to open in 2014. Construction will be financed in part by a $62 million bond issued approved by Joplin voters in April.


Associated Press writer Alan Scher Zagier contributed to this report.