Grass Range, MT has a population of 119 and is the 26,449th largest city in the United States. The population density is 851 per sq mi which is 12359% higher than the Montana average and 839% higher than the national average. The median age in Grass Range is 57 which is approximately 44% higher than the Montana average of 40. In Grass Range, 57% of the population over 15 years of age are married, 97% speak English and 3% speak Spanish. 75% of Grass Range residents were born in Montana, 25% were born out of state, 0% were born outside of the United States and 0% were foreign born.