Ulm is a census-designated place in Cascade County, Montana, United States. It was originally a large ranch owned by Indiana-born cattleman William Ulm. The population was 738 at the 2010 census. It is part of the Great Falls, Montana Metropolitan Statistical Area. The Zip Code is 59485. The post office opened in 1883. In 1887 Ulm became a stop on the Montana Central Railway. A bridge across the Missouri River was built in 1914.