In his farewell address, President Obama urged Americans to unite and said he is committed to working with Donald Trump for a smooth transition of power.

The tradition of presidents giving a farewell address began with George Washington in 1796.

“In 10 days the world will witness a hallmark of our democracy,” the president said January 10, referring to the peaceful transfer of power from one freely elected president to the next. “I committed to President-elect Trump that my administration would ensure the smoothest possible transition, just as President Bush did for me.”

He noted that democracy does not require uniformity of opinion, but does require “a basic sense of solidarity — the idea that for all our outward differences, we are all in this together; that we rise or fall as one.”

Obama said his faith in America had been strengthened over the past eight years and called on citizens “to make sure our government can help us meet the many challenges we still face. … We have everything we need to meet those challenges,” he told the crowd of 18,000 in his hometown of Chicago.

Obama paid tribute to the sacrifices made by his wife and by his daughters, who were young girls when he became president. He praised first lady Michelle Obama for her “grace and grit and style and good humor” and for making the White House “a place that belongs to everybody.”

Acknowledging that “race remains a potent and often divisive force,” the first black president said that race relations are better than they were 10, 20 or 30 years ago.

He urged all Americans to be active guardians of democracy. “If something needs fixing, then lace up your shoes and do some organizing.”

“I leave this stage tonight even more optimistic about this country than when we started. Because I know our work has not only helped so many Americans; it has inspired so many Americans — especially so many young people out there — to believe that you can make a difference; to hitch your wagon to something bigger than yourselves.”

After nearly a decade in the spotlight, Obama will become a private citizen, an elder statesman at 55. He plans to take some time off and write a book.

The Associated Press contributed to this report.