Williston will have a new mayor this summer.
Longtime mayor Ward Koeser has decided to retire from the position.
Koeser took over as mayor in 1994, long before the surge in oil exploration that has transformed the city of Williston.
He says he won't seek reelection this June.
Koeser told the Williston Herald that when he was first elected 20 years ago he had the goal of making Williston the best little city in America.
Today, he is leading the fastest-growing small city in the U.S.
But he says it's time to find someone young with new energy to lead Williston as the oil boom continues.
Another Williston leader is also stepping down - fire chief Alan Hanson has announced he is retiring at the end of January.
Hanson has been fire chief for seven years and expected to hand his retirement notice to the city council this week.