Oak Grove, MO has a population of 7,844 and is the 4,772nd largest city in the United States. The population density is 1,271 per sq mi which is 1372% higher than the Missouri average and 1303% higher than the national average. The median age in Oak Grove is 34 which is approximately 13% lower than the Missouri average of 38. In Oak Grove, 57% of the population over 15 years of age are married, 97% speak English and 2% speak Spanish. 77% of Oak Grove residents were born in Missouri, 23% were born out of state, 0% were born outside of the United States and 0% were foreign born.