Barack Obama's presidency will be recorded in the history books as having begun on January 20, 2009, in Washington, D.C.
In fact, it began on another, colder January night in Dubuque, Iowa. Obama was not in Dubuque that night.
But Brianna Cleland, a 22-year-old teacher, was.
"I really want to make something happen in America," she told me that night. "And the way to do that is with someone new, with someone different, and that's Barack Obama."
Cleland had never caucused before.
Neither had most of the Iowans who joined her at Dubuque County Precinct 19's Democratic presidential caucus in the Mississippi Riverfront city's Carnegie-Stout Library.
For them, and for thousands like them, Obama represented the promise of fundamental, transformational change.
It was not just a matter of breaking with George Bush.
It was a matter of breaking with Bill Clinton, and with the definition of the Democratic party as a managerial institution that was poised to run things for awhile after a more dynamic but less able Republican party had messed up sufficiently to make dull centrism seem appealing.
As Obama takes office, far from Iowa, and far from the political dynamic that was in play last January, he would do well to remember that it was this sense that he would be different that made people like Brianna Cleland brave the cold, and people like 25-year-old Liz Wagner, a high school social studies teacher who caucuses wearing an orange "I Caucus for Darfur" t-shirt that night.
Wagner's shirt may have referenced a neglected region of Africa, but she was really motivated by a deep, genuinely pained frustration with a foreign-policy consensus that saw Democrats joining Republicans in making excuses for humanitarian, diplomatic and strategic failures that culminated with a unwise and unnecessary war in Iraq.
"I'm glad that he was opposed to the Iraq War before it started," Wagner said of Obama. "It shows he has some judgment. That's more that you can say about most of the other candidates or most of the Democrats in Congress."
Wagner was right. Obama might not have run as an anti-war candidate, but he was understood as such. The Iowans who caucused for the young senator from Illinois, giving him the victory that would propel him into serious competition for the presidency, did so because they saw him as the most political viable foe of the Bush doctrine and the disasters it has caused.
It ought never be forgotten that Barack Obama became the Democratic nominee because of his opposition to George Bush's wrongheaded approach to the world.
As a candidate, Obama promised change.
Today, as he assumes the presidency, Obama will continue to promise change.