1951 - Simon served in the United States Army during the Korean War, becoming an intelligence officer.
1955 - He began his political career, serving in the Illinois House of Representatives.
1960 - He married Jeanne Hurley Simon on the 21st of April.
1968 - He moved to the Illinois State Senate.
- He was elected Lieutenant Governor of Illinois.
1969 - His bipartisan teamwork with Ogilvie produced the state's first income tax and paved the way for the state's constitutional convention, which created Illinois's fourth constitution.
1973 - Simon became a professor at Sangamon State University in Springfield.
- Harvard University's John F. Kennedy School of Government.
1974 - He resumed his political career and was elected as a Democrat to the Ninety-fourth Congress.
1984 - He then ran and was elected to the United States Senate.
1987 - He sought the Democratic nomination for president, narrowly losing the Iowa Caucus to Rep. Richard Gephardt of Missouri.
1990 - He won re-election to the U.S. Senate by defeating Congresswoman Lynn Martin with 65 percent of the vote and by nearly 1 million votes — the largest plurality of any contested candidate for senator or governor of either party that year.
1994 - He was an outspoken critic of President Bill Clinton's response to the Rwandan genocide.
- He is, together with Jim Jeffords, credited by Canadian Lieutenant-General Roméo Dallaire, Force Commander of the United Nations Assistance Mission for Rwanda, for actively lobbying the U.S. administration into mounting a humanitarian mission to Rwanda during the genocide.
1996 - He and libertarian researcher Dave Kopel co-authored an article in National Law Journal denouncing the practice.
2003 - Died in Springfield, Illinois following heart surgery at the age of 75 on the 9th of December.