"A New Birth of Freedom", a phrase from the Gettysburg Address, served as the inaugural theme to commemorate the 200th anniversary of the birth year of Abraham Lincoln. In his speeches to the crowds, Obama referred to ideals expressed by Lincoln about renewal, continuity and national unity. Obama mentioned these ideals in his speech to stress the need for shared sacrifice and a new sense of responsibility to answer America's challenges at home and abroad.
Obama and others paid homage to Lincoln in the form of tributes and references during several of the events, starting with a commemorative train tour from Philadelphia, Pennsylvania to Washington, D.C. on January 17, 2009. The inaugural events held in Washington, D.C. from January 18 to January 21, 2009 included concerts, a national day of community service on Martin Luther King, Jr. Day, the swearing-in ceremony, luncheon and parade, inaugural balls, and the interfaith inaugural prayer service. The presidential oath as administered to Obama during his swearing-in ceremony on January 20 strayed slightly from the oath of office prescribed in the United States Constitution, which led to its re‑administration the next evening.
In addition to a larger than usual celebrity attendance, the Presidential Inaugural Committee increased its outreach to ordinary citizens to encourage greater participation in inaugural events compared with participation in recent past inaugurations. For the first time, the committee opened the entire length of the National Mall as the public viewing area for the swearing-in ceremony, breaking with the tradition of past inaugurations. Selected American citizens participated in the train tour and other inaugural events, and a philanthropist organized a People's Inaugural Ball for disadvantaged people who otherwise would be unable to afford to attend the inaugural festivities. Among the celebrations for the inauguration, the committee hosted a first-ever Neighborhood Inaugural Ball with free or affordable tickets for ordinary citizens.