Blue River, WI has a population of 429 and is the 20,478th largest city in the United States. The population density is 471 per sq mi which is 438% higher than the Wisconsin average and 420% higher than the national average. The median age in Blue River is 49 which is approximately 26% higher than the Wisconsin average of 39. In Blue River, 57% of the population over 15 years of age are married, 99% speak English and 1% speak Spanish. 80% of Blue River residents were born in Wisconsin, 19% were born out of state, 1% were born outside of the United States and 0% were foreign born.