Wilder is a city in Canyon County, Idaho, United States. The population was 1,533 at the 2010 census. Wilder is part of the Boise City–Namp…Wilder is a city in Canyon County, Idaho, United States. The population was 1,533 at the 2010 census. Wilder is part of the Boise City–Nampa, Idaho Metropolitan Statistical Area. Wilder was established in 1919, and was named for Marshall P. Wilder, a magazine editor.