The Friday File: This Monday, Governor Terry Branstad of Iowa will become the longest serving governor in US history at 7,640 days, almost 21 years, and will surpass the long held record of Vice President and Revolutionary War General George Clinton of NY. Number three is William Janklow of SD at a mere 5,851 days or slightly more than 16 years, followed by George Wallace of AL at 5,848 days.