what county is new plymouth id in
New Plymouth, ID. Online Offers. New Plymouth is a city in Payette County, Idaho, United States. The population was 1,400 at the 2000 census. It was incorporated on February 15, 1896. It is the host of the annual Payette County Fair. New Plymouth is part of the Ontario, ORâID Micropolitan Statistical Area. New Plymouth was a colony town, bought and planned before it was settled.