How long did Greg Gianforte's predecessor serve as U.S. representative for Montana's at-large congressional district?
Greg Gianforte:  On May 25, 2017, he won the special election following Rep. Ryan Zinke's resignation to become Secretary of the Interior. Ryan Zinke:  Zinke served as the U.S. representative for Montana's at-large congressional district from 2015 until 2017.
i don't know