Gallatin Gateway, MT has a population of 794 and is the 16,654th largest city in the United States. The population density is 136 per sq mi which is 1888% higher than the Montana average and 50% higher than the national average. The median age in Gallatin Gateway is 48 which is approximately 19% higher than the Montana average of 40. In Gallatin Gateway, 57% of the population over 15 years of age are married, 100% speak English and 0% speak Spanish. 33% of Gallatin Gateway residents were born in Montana, 64% were born out of state, 2% were born outside of the United States and 0% were foreign born.