What Does “On the Wagon” Mean & Where Did It Originate?

According to the University of Indiana (Indiana Prevention Resource Center), supporters of the temperance movement drove around a wagon of water from saloon to saloon encouraging bar patrons to get on the wagon and drink water instead of alcohol. ‘Off the wagon’ means a person is participating in drinking and ‘on the wagon’ indicates they are refraining from alcohol.

Other resources suggest that the water wagons would come through town hosing down the streets to keep the dust from getting out of hand. So if you were sitting atop this wagon, you were drinking water, not alcohol.