In late March, 2017, Scott Donahue, Mayor of Emeryville, California, changed his registration from the Democratic Party to the Green Party. He was elected to the city council for the first time in 2014 and is serving a four-year term. Emeryville voters do not vote directly for Mayor; they elect five members to the council, and the council chooses the Mayor. Donahue was chosen Mayor in late 2016.
Emeryville has a population of 10,000 and is a neighbor of Oakland and Berkeley.
Yay, excellent!
Gayle McLaughlin, member of the Green Party, was mayor of nearby Richmond, CA from 2007 to 2015. Richmond is a larger city with a population of 100,000.