Janesville, MN has a population of 2,674 and is the 9,418th largest city in the United States. The population density is 1,528 per sq mi which is 2370% higher than the Minnesota average and 1587% higher than the national average. The median age in Janesville is 34 which is approximately 11% lower than the Minnesota average of 38. In Janesville, 66% of the population over 15 years of age are married, 97% speak English and 2% speak Spanish. 86% of Janesville residents were born in Minnesota, 12% were born out of state, 0% were born outside of the United States and 2% were foreign born.