The Mayor was the leader of Michel Delving, a town in the White Downs. The position was usually elected, but it could also be handed down by birthright. The mayor also presided over large events where leadership was wanted or necessary.
The Mayor of Michel Delving was elected for seven-year terms. He was the only official in the Shire to be elected, unlike the hereditary title of the Thain. He was chosen at the Free Fair at the Lithe, held every seven years at the White Downs. His primary duty was to preside over banquets during Shire-holidays.
The Mayor of Michel Delving's importance increased during the late Third Age, as the office accumulated the roles of Postmaster and First Shirriff. Thus, the Mayor managed the Messenger Service and the Watch. The office of Mayor had become the most important position in the Shire and its title-holder became the only real official in the Shire, so that the position was also known as Mayor of the Shire. The town of Michel Delving became the Shire's seat of government.
Will Whitfoot was the mayor at the time of the War of the Ring; however, he was imprisoned by Saruman in the Lockholes. Frodo Baggins acted as Deputy Mayor while Mayor Will Whitfoot recovered from his imprisonment in the Lockholes.
Beginning in FO 13 (SR 1434), King Elessar made the Mayor along with the offices of the Thain and Master of Buckland counsellors of the North-kingdom. Sam Gamgee was elected Mayor of the Shire seven times between SR 1427 (FO 55) and and SR 1476 of the Shire Reckoning.