Oak Hills, OR has a population of 11,678 and is the 3,490th largest city in the United States. The population density is 7,464 per sq mi which is 18749% higher than the Oregon average and 8139% higher than the national average. The median age in Oak Hills is 34 which is approximately 12% lower than the Oregon average of 39. In Oak Hills, 59% of the population over 15 years of age are married, 78% speak English and 6% speak Spanish. 39% of Oak Hills residents were born in Oregon, 39% were born out of state, 2% were born outside of the United States and 20% were foreign born.