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Obama's last trip on Air Force One will be a pilgrimage to his adoptive hometown, where he will address a sell-out crowd not far from where he accepted the presidency eight years ago.
Diehard fans -- many African American -- have braved Chicago's frigid winter to collect free tickets, which now sell for upwards of $1,000 (R13,627) apiece on Craigslist.
First Lady Michelle Obama, Vice-President Joe Biden and his wife, Jill, will go along on for the ride.
Obama's cross-country trek would be a sentimental trip down memory lane were it not slap-bang in the middle of a tumultuous presidential handover.
Trump has smashed conventions, vowed to efface Obama's legacy and hurled personal insults left and right.
The 2016 election campaign has raised serious questions about the resilience of US democracy.
In a virtually unprecedented move, US intelligence has accused the Kremlin of tipping the electoral scales in Trump's favour.
Democrats, cast into the political wilderness with the loss of the White House, the Senate and the House of Representatives plus a majority of statehouses, are struggling to regroup.
With an approval rating hovering around 55 percent, Obama will hope to steel them for new battles ahead.
Lead speechwriter Cody Keenan said the address would be about Obama's vision for where the country should still go.
"It's not going to be like an anti-Trump speech, it's not going to be a red meat, rabble-rousing thing, it will be statesman-like but it will also be true to him," Keenan told AFP. "It will tell a story."
Life after White House
Trump's unorthodox politics has thrown 55-year-old Obama's transition and post-presidency plans into flux.
Obama, having vowed a smooth handover of power, finds himself being increasingly critical of Trump as he prepares to leave office on 20 January.
After that there will still be a holiday and an autobiography, but Obama could find himself being dragged backed into the political fray if Trump were to enact a Muslim registry or deport adults brought to the United States years ago by their parents.
Having vowed to take a back seat in politics, Obama's second act could yet be as politically engaged as Jimmy Carter -- whose post-presidency has remade his image as an elder statesman.
Many Obama aides who had planned to take exotic holidays or launch coffer-replenishing forays into the private sector are also reassessing their future and mulling a return to the political trenches.
Obama's foundation is already gearing up for a quasi-political role -- funnelling idealistic youngsters into public life.
Presidents since George Washington have delivered a farewell address of sorts.
Washington's final 7,641-word message -- which is still read once a year in the Senate by tradition -- contained warnings about factionalism and interference by foreign powers that seem oddly prescient.
But speechwriter Keenan sees few obvious templates: "Bush and Clinton did theirs from here (the White House), George HW Bush went to West Point, gave a foreign policy speech," he told AFP. "They are all totally different."
The trip to Chicago is not just for nostalgia, Keenan indicated.
"The thread that has run though his career from his days as community organizer to the Oval Office is the idea that if you get ordinary people together and get them educated, get them empowered, get them to act on something, that's when good things happen," he said.
"For him, as someone who started as a community organiser, whose campaign was powered by young people, ordinary people, we decided we wanted to go back to Chicago."
"Chicago is not just his hometown, it's where his career started."
And now it is also where Obama's presidential career will effectively end.