Oak Grove, MN has a population of 8,334 and is the 4,555th largest city in the United States. The population density is 246 per sq mi which is 297% higher than the Minnesota average and 171% higher than the national average. The median age in Oak Grove is 42 which is approximately 10% higher than the Minnesota average of 38. In Oak Grove, 68% of the population over 15 years of age are married, 92% speak English and 5% speak Spanish. 81% of Oak Grove residents were born in Minnesota, 15% were born out of state, 1% were born outside of the United States and 3% were foreign born.