North Powder is a city in Union County, Oregon, United States. The population was 439 at the 2010 census. North Powder was platted in …North Powder is a city in Union County, Oregon, United States. The population was 439 at the 2010 census. North Powder was platted in 1885 or 1886 along the Oregon Railroad and Navigation Company rail line, having been a stage stop before then.