Circle, MT has a population of 548 and is the 19,004th largest city in the United States. The population density is 699 per sq mi which is 10141% higher than the Montana average and 672% higher than the national average. The median age in Circle is 51 which is approximately 27% higher than the Montana average of 40. In Circle, 75% of the population over 15 years of age are married, 99% speak English and 0% speak Spanish. 73% of Circle residents were born in Montana, 24% were born out of state, 3% were born outside of the United States and 0% were foreign born.