(Updated 1:10 p.m, March 14, 2008)
Connecticut Gov. John Rowland (R) is the tenth governor in the nation's history to quit under the cloud of a criminal investigation but without being impeached.
Rowland resigned Monday evening, truncating his third term, and avoiding the possibility of being impeached and removed from office. Seven governors have been impeached and removed between 1871 and 1988. Arizona's Evan Mecham (R) was the last governor to face that fate in 1988 and the only governor in the past 75 years to be convicted on articles of impeachment.
In addition to the scrutiny of impeachment hearings by the Connecticut House of Representatives, Rowland and his administration are under federal investigation for steering state contracts to political allies and companies in exchange for gifts, including renovations to the governor's vacation home.
The most recent governor to resign under pressure was Arizona Republican Fife Symington (R), who left office in 1997 after being convicted of federal bank and wire fraud charges that were later overturned.
Also in the past decade, Gov. Jim Guy Tucker (D) of Arkansas resigned in July 1996 after being convicted of two felony charges related to the "Whitewater" investigations. Legislative leaders and the lieutenant governor had called for impeachment proceedings.
And Alabama Gov. Guy Hunt (R) was legally removed from office in 1993 after being convicted of illegally using campaign and inaugural funds to pay personal debts.
Other governors who resigned amid controversy:
Although he didn't resign from office, Oklahoma Gov. David Walters (D) reluctantly opted not to run for re-election in 1994 after a grand jury recommended impeachment. Walters eventually pled guilty to a misdemeanor campaign finance violation.
In the nation's history, only 15 governors have been impeached, including two who were impeached twice, but only seven of those were removed from office, according to the Connecticut Office of Legislative Research. A state House of Representatives must vote to impeach - indict - a governor, and the state Senate then tries and votes on conviction and removal.
Twice impeached were Oklahoma Gov. Henry S. Johnson(D), who was tried in 1927 and impeached and removed in 1929, and Florida Gov. Harrison Reed (R), who survived impeachments in 1868 and 1872 without being convicted.
Besides Arizona's Mecham and Johnson of Oklahoma, five other governors have been removed from office after impeachment:
Three other governors faced impeachment but left office in another fashion. Mississippi Gov. Adelbert Ames (R) resigned after being impeached in 1876 but before the Legislature could convict and remove him.
Two North Dakota governors, William Langer (R) in 1934 and Thomas H. Moodie (D) in 1935, faced impeachment charges but were removed by the state's Supreme Court. Remarkably, Langer was re-elected as governor in 1937 and also elected to the U.S. Senate in 1940.
In recent political history, governors are more likely to resign because of a criminal investigation than a legislature's impeachment inquiry, said Al May, director of George Washington University's school of media and public affairs.
The enforcement mechanisms of most state legislatures are relatively weak, and they have been unwilling to enforce tough ethical standards on governors or themselves, May told Stateline.org.
Political science professor Scott McLean of Quinnipiac University in Hamden, Conn., said that the Connecticut General Assembly also was reluctant to pursue impeachment against Rowland, even with mounting evidence and political pressure.
Like other statehouses and even the U.S. Congress, Connecticut politicians are worried about triggering a vicious, partisan exchange of investigations and counter-charges, McLean said. "One should not throw stones, if one lives in a glass state house."
Editor's note: A previous version of this story incorrectly said that President Ronald Reagan (R) pardoned former Maryland Gov. Marvin Mandel (R). The story has been corrected to say that Reagan commuted Mandel's sentence and his conviction was overturned in 1987. Stateline.org regrets the error.