President Obama will say farewell Tuesday night to a nation he helped transform during his eight years in the White House.

Riding high in the polls but just days away from handing over the reins to a Manhattan mogul who has vowed to dismantle much of his legacy, Obama has chosen to make his final address as commander-in-chief in the city where he launched his unlikely and boundary-breaking political career — Chicago.

There Obama, who won the White House for the first time in 2008 on the message of "hope and change," will tell the supporters who have been with him from the start to take heart and not despair as he lays out what White House spokesman Josh Earnest is calling a "forward-looking" vision for America.

"America is a story told not minute to minute, but generation to generation," Obama wrote in a Facebook post advancing the speech, which he wrote himself. "We've made America a better, stronger place for the generations that will follow. We've run our leg in a long relay of progress, knowing that our work will always be unfinished. And we've reaffirmed the belief that we can make a difference with our own hands, in our own time."

Speaking to NBC News' Lester Holt Tuesday aboard Air Force One, President Obama said he hoped he could properly convey the gratitude he felt, both for his staff and his supporters.

"You know when you when you reflect back on eight years, for all the highs and the lows, the one thing that is a constant is the incredible dedication of the people who got you there," Obama said, adding that he meant everyone from his staff to "the people who, you know, would say that the work we did made a difference."

"I think that that sense of gratitude that I feel for those folks, I just hope I'm able to express that," he said.

For Obama, the address before a hometown crowd will cap a long goodbye during which he's reminded Americans where the nation was back in 2008, when the economy was in free fall and the country was mired in two unpopular wars — and how far the country has come since then.

Obama is likely to buttress his case with a battery of statistics as he touts the accomplishments of his two terms, which among other things includes a record 75 straight months of job growth, more than 15 million new jobs, a long-awaited rise in hourly wages — and the removal of Osama Bin Laden as a threat to America.

And, Earnest said, Obama will talk about "fairness and justices" and "the challenges that lie ahead."

"I can tell you, in general, that the President is committed to delivering a forward-looking speech that will examine briefly the significant progress that our country has made in the last eight years," he told reporters during a briefing on Monday. "But it will take a closer look and he'll spend more time talking about what the President believes is necessary for us to confront the challenges that lie ahead."

The Obamas have welcomed the Trumps to the White House, stressed national unity and chosen to focus on the smooth transition of power.

First Lady Michelle Obama, who like her husband remains a widely popular public figure, had tears in her eyes last week as she delivered a stirring goodbye speech.

"Being your first lady has been the greatest honor of my life," she said. "And I hope I made you proud."

Obama will deliver his speech at McCormick Place, which sits on the city's lakefront and is the largest convention center in North America. Some 14,000 people are expected to attend, the Chicago Tribune reported.

More of Lester Holt's interview with Obama will air in a one-hour NBC News primetime special that airs this Friday at 10 p.m. ET, right here on Channel 3.