November 4, Lincoln marries Mary Todd.
Abraham Lincoln forms a law partnership with William H. Herndon.
Lincoln is elected a member of congress to the 30th Congress of the United States. As a result Lincoln goes from being a local politician to one with national significance.
As a Congressman, Lincoln introduced the "Spot Resolutions" in response to the war between Mexico and the United States. Lincoln's resolution called into question whether the "spot" where American blood had been shed in a border dispute with Mexico was really American territory, thus calling into question one of the justifications for the war. Lincoln's criticism of the war earned him the derisive nickname of "Spotty Lincoln" in one Illinois newspaper.
In 1848 Lincoln was a presidential elector on the Whig ticket and he campaigned on behalf of the party in New England, for Taylor. This allowed Lincoln to gain more name recognition beyond the frontier area.
In December, Lincoln attended the second session of the Thirtieth Congress where he voted for the Wilmot Proviso, which would have banned slavery in any territory acquired from Mexico as a result of the war, and Ashmon's Amendment.
In a significant move which would define Lincoln as anti-slavery, he introduced an bill abolishing slavery in the federal District of Columbia.
Lincoln tried to get appointed as Commissioner of the general Lands Office, but he failed.
Lincoln was instead offered appointment as the territorial governor of Oregon, but he declined. It is interesting to ponder how the course of history would have been different if Lincoln had been removed from the public eye by sending him to remote Oregon.
Later in the year Lincoln returned to Springfield, dispirited and disillusioned by his stay in Washington.