Governor William Janklow
Served: 1979-1987, 1995-2003 Length of Service: 16years 0 months 7 days, 5651 days State: South Dakota Party: Republican William John "Bill" Janklow was an American politician and member of the Republican Party who holds the record for the longest tenure as Governor of South Dakota - sixteen years in office. Janklow has the second longest gubernatorial tenure in post-Constitutional U.S. history at 5,851 days. Janklow served as the 25th Attorney General of South Dakota from 1975 to 1979 before serving as the state's 27th Governor from 1979 to 1987 and then the 30th Governor from 1995 to 2003. Janklow was then elected to the United States House of Representatives, where he served for a little more than a year. He resigned in 2004 after being convicted of manslaughter for his culpability in a fatal automobile accident.