Oshkosh, WI has a population of 66,713 and is the 556th largest city in the United States. The population density is 2,494 per sq mi which is 2752% higher than the Wisconsin average and 2652% higher than the national average. The median age in Oshkosh is 34 which is approximately 14% lower than the Wisconsin average of 39. In Oshkosh, 41% of the population over 15 years of age are married, 95% speak English and 2% speak Spanish. 78% of Oshkosh residents were born in Wisconsin, 18% were born out of state, 0% were born outside of the United States and 3% were foreign born.