DES MOINES, Iowa - Iowa Gov. Terry Branstad - a graying little man who relies on Midwestern stick-to-itiveness rather than personal flair - is about to enter the political record books as the longest-serving governor in American history, dating all the way back to colonial times.

On Dec. 14, the six-term Republican will mark his 7,642d day of service as governor. That's just shy of 21 years in the office. Branstad will move beyond former New York Gov. George Clinton, whose service includes some pre-Constitution time, and is far out in front of any recent or current governor.

The milestone is a testament to the fact that while political fashions have changed in the last three decades, this serious son of small-town farmers has managed to remain relevant. And it comes at a political moment when the contrast between Branstad and the high-wattage stars of the GOP is on display in Iowa, as hordes of candidates flood the state before the leadoff presidential caucuses.

Unlike many of the 2016 hopefuls touring Iowa, Branstad is not a culture warrior, a business tycoon, or a policy maven. He's an old-fashioned retail politician who visits all of Iowa's 99 counties every year. His schedule is jammed with tours of mom-and-pop businesses, keynote speeches at trade shows, talks at rural schools, and the signing of seemingly endless proclamations on everything from motorcycles to college applications.

"He's everywhere. People say 'he came to our ribbon-cutting,' " said Bonnie Campbell, a former Democratic attorney general who ran unsuccessfully against Branstad in 1994. "Everybody feels they know him."

Most other long-serving governors topped out at four four-year terms, including Bill Janklow in South Dakota, George Wallace in Alabama, Jim Rhoads in Ohio, and Jim Hunt in North Carolina. All served more than one stint in the office.

Helping Branstad, 69, go longer is that Iowa is a rare state without a term-limits law. Also, he has never sought higher office. He took a break in the private sector after serving four terms from 1983 to 1999, but came back to oust a Democratic incumbent in 2010.

"The odds of anyone passing him in the 21st century are next to none," said Eric Ostermeier, a research associate at the University of Minnesota who has compiled a comprehensive list of governors' length of service.

David Yepsen, a former Des Moines Register political reporter who knew Branstad when both were University of Iowa undergraduates in 1960s, said Branstad had his own style as a student and as a young state lawmaker.

"He was this right-wing kid from northern Iowa," said Yepsen, now director of the Paul Simon Public Policy Institute at Southern Illinois University, adding, "a lot of elites dismissed him or ridiculed him."

Branstad said in an interview that while others in the 1960s wanted to tear down the system, "I hoped someday to be part of it."

And in Iowa, his hint of nerdiness would never be a problem.

Branstad's brand of Republicanism can seem charmingly old-fashioned in today's GOP. He talks about government stability and working out compromises, which comes in handy since Democrats control the Senate. In recent years, Branstad and lawmakers have cut property taxes, but also raised the gasoline tax to pay for infrastructure.