Obama taught constitutional law at the University of Chicago Law School for twelve years, being first classified as a Lecturer from 1992 to 1996, and then as a Senior Lecturer from 1996 to 2004.[32] He also joined Davis, Miner, Barnhill & Galland, a twelve-attorney law firm specializing in civil rights litigation and neighborhood economic development, where he was an associate for three years from 1993 to 1996.

In 1996, Obama was elected to the Illinois Senatesucceeding State Senator Alice Palmer as Senator from Illinois' 13th District, which then spanned Chicago South Side neighborhoods from Hyde Park-Kenwood south to South Shore and west to Chicago Lawn.[36] Once elected, Obama gained bipartisan support for legislation reforming ethics and health care laws. On February 10, 2007, Obama announced his candidacy for President of the United States in front of the Old State Capitol building in Springfield, Illinois.

Obama met his wife, Michelle Robinson, in June 1989, when he was employed as a summer associate at the Chicago law firm of Sidley Austin.[159] Assigned for three months as Obama's adviser at the firm, Robinson joined him at group social functions, but declined his initial offers to date.[160] They began dating later that summer, became engaged in 1991, and were married on October 3, 1992.[161] The couple's first daughter, Malia Ann, was born in 1998,[162] followed by a second daughter, Natasha ("Sasha"), in 2001.

On November 4, 2008, Barack Obama defeated John McCain in the general election and became the first African American to be elected President of the United States.[117][118][119][120] In his victory speech, delivered before a crowd of hundreds of thousands of his supporters in Grant Park in Chicago, Obama proclaimed that "change has come to America."[121] Born in Hawaii, Obama will be the first U.S. President born outside the contiguous United States. He also will be fifth youngest President at a date of accession, and the first since Lincoln whose primary political base is Illinois.