Obama's call to unity after decades of political division echoed Abraham Lincoln's first inaugural address in 1861.

CNN: Schneider: Tone of Obama speech right for the times

In January 1789 George Washington put quill to paper and, in consultation with aide David Humphreys, drafted his first inaugural address.

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At a little more than 2, 100 words, Obama's speech was about 300 shorter than his first inaugural address four years earlier.

CNN: Obama's speech ties current issues to founding principles

Similarly, instead of talking about his commitment to "Global Zero, " a vision of a world without nuclear weapons that he committed to in his first inaugural address and his Prague speech in April 2010, he again focused on a set of smaller steps.

CNN: Obama dares Congress to get the job done

According to observers, it was the first time a president championed gay marriage in an inaugural address.

CNN: Obama's speech ties current issues to founding principles

He surrounded himself with seasoned if fractious advisers, and during his first weekend in Washington he asked Seward to look over his Inaugural Address.

NEWYORKER: Union Man

Three sentences into his inaugural address four years ago, Barack Obama made the first mistake of his presidency.

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January 2013: Obama becomes the first U.S. president to mention gays and lesbians in an inaugural address and champions same-sex marriage.

CNN: The evolution of the nation's 'first gay president'

The nation's first African-American president will become only the 17th U.S. leader to deliver a second inaugural address, before he joins the traditional parade up Pennsylvania Avenue to the White House.

CNN: Obama sworn in to second term

The nation's first African-American president also will become only the 17th U.S. leader to deliver a second inaugural address before joining the traditional parade up Pennsylvania Avenue to the White House.

CNN: Obama officially begins 2nd term on Sunday