Before you ask: No, John Denver is not the city’s namesake.
Denver does owe its name from another man with the initials J.D., though. James William Denver was a Civil War general, a territorial governor and the eponym for the Mile High City.
While he was the territorial governor of the Kansas Territory, Denver played a role in appointing several county officials and a sheriff in what would become the county seat of Colorado’s Eastern Plains. Two of those appointees also have familiar names to Denverites — Ned Wynkoop and William H. Larimer.