The other 322 senators who resigned, in charts

Al Franken's full Senate floor speech
Al Franken's full Senate floor speech

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  • Most senators have resigned to fill other government posts
  • Two in three resignations happened before the end of the Civil War
  • Only four senators besides Franken have resigned due to scandal over the last century

Washington (CNN)Al Franken will become the 323rd member of the Senate to resign from office in the coming weeks. But what do we know about the 322 who came before him?

Resignations amid scandals are rare: Before Franken, only four Senators had called it quits in the midst of a scandal in the last century, according to a list of resignations from the Senate Historical Office.
    Franken, D-Minnesota, announced on Thursday that he'd leave his post in the coming weeks after being accused of inappropriately touching multiple women before and after he was a senator. More than two dozen Democratic senators called for his resignation Wednesday, and an Ethics Committee investigation was already underway.
    But a majority of the resignations since the country was founded have happened because the senator was moving to another government post. Here's a full breakdown with data from the Senate Historical Office:
    Nearly a quarter of the resignations (23%) have happened for some kind of executive branch appointment, while about a seventh (14%) quit to run for governor or another state or local office. About one in ten (11%) quit to join a federal or state or local judiciary and 7% quit for a diplomatic appointment. The number of those moving to an executive branch post has climbed dramatically, from 15% before 1850 to 34% since 1850.
    About one in eight (12%) quit for some private pursuit outside of government. Another 6% quit because of an illness, and 5% withdrew after secession during the Civil War. Another 3% resigned over scandal and 2% resigned after a clash with their state legislatures, back before the direct election of senators, which was enshrined for all 50 states by the 17th Amendment in 1913. Reasons for 13% of the resignations are unclear, according to the Senate Historical Office, but nearly all of them occurred before 1850. The most recent "unclear" resignation was Mel Martinez, the Florida Republican senator who left in 2009.
    "There is no impending reason; it's only my desire to move on and to get on with the rest of my life," Martinez said at the time.
    Unlike Martinez, Franken did not want to go.
    "Today I am announcing that in the coming weeks I will be resigning as a member of the United States Senate," Franken said from the Senate floor, before turning to hit Trump. "I, of all people, am aware that there is some irony in the fact that I am leaving, while a man who has bragged on tape about his history of sexual assault sits in the Oval Office, and a man who has repeatedly preyed on young girls campaigns for the Senate with the -- with the full support of his party."
    Senators resigned at much faster rates earlier in the country's history as well. Two in three resignations took place before the end of the Civil War, while only 31 senators have resigned in the last half century, mostly to fill other government positions.
    The last to resign amid a scandal was Sen. John Ensign, R-Nevada, in 2011, who quit during an investigation by the Ethics Committee into his affair with a former campaign staffer who was married to a Senate staffer. Before that, Sen. Robert Packwood, R-Oregon, resigned after being recommended for expulsion amid accusations of sexual abuse in 1995.
    Going farther back, Sen. Harrison Williams, D-New Jersey, resigned in 1982 after being recommended for expulsion after a bribery conviction. In 1922, Sen. Truman Newberry, R- Michigan, resigned after a conviction for election irregularities that was later reversed. William Clark, D-Montana, resigned for bribery in 1900 and Alexander Caldwell, R-Kansas, for election irregularities in 1873.
    The states with the most resignations are Massachusetts with 20, then Georgia, Virginia, South Carolina and New York. Franken will be the 4th to resign from Minnesota.
    A few of the most recent senators to call it quits include Alabama's Jeff Sessions earlier this year, Oklahoma's Tom Coburn in 2015, Montana's Max Baucus in 2014, Massachusetts' John Kerry in 2013, South Carolina's Jim DeMint in 2012, Nevada's Ensign in 2011, plus Illinois' Barack Obama, Delaware's Joe Biden, New York's Hillary Clinton and Colorado's Ken Salazar during the 2008-09 presidential transition.