St. Peter, WI has a population of 1,497 and is the 12,695th largest city in the United States. The population density is 412 per sq mi which is 372% higher than the Wisconsin average and 355% higher than the national average. The median age in St. Peter is 42 which is approximately 6% higher than the Wisconsin average of 39. In St. Peter, 79% of the population over 15 years of age are married, 98% speak English and 1% speak Spanish. 93% of St. Peter residents were born in Wisconsin, 5% were born out of state, 1% were born outside of the United States and 1% were foreign born.