New Plymouth is a city in Payette County, Idaho, United States. The population was 1,538 at the 2010 census, up from 1400 in 2000. It was incorporated on February 15, 1896. It is the host of the annual Payette County Fair and rodeo.
New Plymouth is part of the Ontario, OR–ID Micropolitan Statistical Area.
New Plymouth was a colony town, bought and planned before it was settled. It was the combined project of a group of people purportedly dissatisfied with city life in Chicago, who in 1895 formed what they called "The Plymouth Society of Chicago" and William E. Smythe, who was the chairman of the executive committee of the National Irrigation Congress and a famous irrigation promoter. Mr. Smythe was determined to found a colony to serve as a striking argument in favor of his project - irrigation. He spoke throughout the east, urging young and old men to go west in colonies and develop the country with the help of irrigation.