Lincoln secured his place in history by declaring slaves free in 1863
In 2009 the US not only inaugurated its first black president - it also honoured the president who paved Barack Obama's way to the country's highest post.
Events across the nation marked the bicentennial of Abraham Lincoln's birth, celebrating a man widely seen as the greatest US president - the secular saint who redeemed America's original sin of slavery.
Mr Obama has been compared to Lincoln - the lanky junior politician from Illinois who captured the presidency on the strength of his oratory, proving that anyone can make it to the White House.
But amid the commemorations, it is easy to forget that Lincoln - a civil-war president - never lacked for critics. Even in this anniversary year, there has been vigorous debate over his legacy.
One lingering source of controversy among historians is Lincoln's moderation on the slavery issue.
Harvard University's Donald Yacovone says complexities have been lost in celebrations that have focused on hero worship.
"A lot of it is superficial," Mr Yacovone told BBC News. "A lot of it is blind to real, not imagined faults that Lincoln represented."
Mr Yacovone and Henry Louis Gates, one of the most prominent African-American scholars, have co-edited a volume of Lincoln's writings on race and slavery.
Despite his visceral hatred of slavery, Mr Yacovone says, Lincoln - like the overwhelming majority of his contemporaries - never believed in the equality of races.
"He supported enactment of the anti-fugitive slave law, he supported exclusion of black jurors and all basic civil rights," Mr Yacovone says.
He notes that African-Africans were cool about Lincoln in the 1860 election. The leading US black newspaper at the time reacted to his election by expressing "despair of our future".
Born February 1809
Representative for Illinois, 1847-1849
Elected president 1860, pledging to keep slavery in the South
Faced secession from 11 states 1861
Proclaimed emancipation of all slaves 1863
Assassinated April 1865
Lincoln believed until late in the Civil War that he did not have the right to abolish slavery where it existed, and that the only constitutional way to fight it was to oppose its extension.
He once said he might take 100 years to get rid of slavery.
"He was willing to have blacks endure that to preserve the Union and to avoid a Civil War," Mr Yacovone says.
Lincoln, moreover, supported the policy of "colonisation" - removing blacks from North America. "If you're a black American in 1860, what in that programme could you support?" Mr Yacovone asks.
The idea that Lincoln was a reluctant emancipator is not new. Several radical academics have argued this since the 1960s - as did a 2000 book, Forced into Glory, by the editor of Ebony Magazine, Lerone Bennett.
To most historians such criticism is wide of the mark. Civil War scholar James McPherson says Lincoln's moderation was a matter of political necessity.
"Lincoln was a master of the art of the possible and he moved as fast as was possible on the slavery question without alienating support that he could not afford to lose along the way," he told BBC News.
Ronald White, author of A Lincoln: A Biography, says the idea that Lincoln was a man of his time and a moderate is a "truism".
Lincoln's main quality, he says, was his ability to change his mind. "The dogmas of the quiet past are inadequate to the stormy present," Lincoln said a month before the landmark Emancipation Declaration in January 1863. "As our case is new, so we must think anew, and act anew."
Mr White says: "Today we regard this as flip-flopping - but I'm all for people who flip-flop."
Another key to Lincoln's greatness, he adds, is his use of language. He is one of those few leaders whose words still strike a deep chord across the centuries.
On the first anniversary of 9/11, when New Yorkers looked for a historical text that would give voice to their feelings, Governor George Pataki, standing at Ground Zero, read Lincoln's Gettysburg address, which includes the words:
"We cannot dedicate, we cannot consecrate, we cannot hallow this ground. The brave men, living and dead, who struggled here, have consecrated it, far above our poor power to add or detract."
Lincoln may have had less than a year of formal education, Mr White says, but somehow his words last: "There's a timelessness about them".
However perhaps the most heated recent Lincoln controversy has not been over race, but the nature of political greatness.
In a mammoth article in the New Republic magazine, Princeton historian Sean Wilentz criticised both the "defamatory image" of Lincoln as a racist and the "awestruck hagiographies that have become ubiquitous in this anniversary year".
"The American intelligentsia for the most part is still looking for some kind of figure than can float above politics, that can bring real principle to government, that was uncompromising. And they imagine great leaders of the past have had those attributes, which is just wrong," Mr Wilentz says.
This "do-gooder, liberal strand in American politics" - as Mr Wilentz describes it - is as old as the Republic but experienced a resurgence in the 1960s. "It's a high-minded politics that is in fact anti-politics," he says.
Among scholars, Mr Wilentz says, this bias has recently led fans to overemphasise Lincoln's skills as a writer - the result, he contends, is an "aestheticised president" that "now belongs to the English department".
Mistrust of conventional politics, he contends, has also led Lincoln sceptics to give credit for the abolition of slavery to activist figures - who are generally seen by many as the history-making heroes, as opposed to mere machine politicians.
Mr Wilentz' article drew fierce responses, with some countering that his critique was motivated by bitterness at the outcome of the 2008 Democratic primaries (Mr Wilentz supported Washington insider Hillary Clinton against Mr Obama).
Barack Obama used the "Lincoln Bible" for his own swearing in
Perhaps inevitably, current politics and historical remembrance have become intertwined.
Mr Obama himself has encouraged parallels by quoting Lincoln in some of his early speeches.
For his swearing in, he chose the copy of the Bible Lincoln had used in 1861.
Whether or not such parallels are helpful is a matter of debate. Mr White believes current comparisons between Mr Obama's lengthy consultations on Afghan strategy and Lincoln's unhurried approach to making war decisions are valid.
"Lincoln would say to him - take your time'," Mr White says. "I'm afraid that our 24/7 news cycle doesn't give our leaders the time to really think about these issues."
Mr Wilentz is more critical of such parallels. Early comparisons between the 16th president and the 44th, he says, were "campaign branding".