Greendale, MO has a population of 639 and is the 18,042nd largest city in the United States. The population density is 3,175 per sq mi which is 3575% higher than the Missouri average and 3404% higher than the national average. The median age in Greendale is 49 which is approximately 28% higher than the Missouri average of 38. In Greendale, 46% of the population over 15 years of age are married, 93% speak English and 0% speak Spanish. 66% of Greendale residents were born in Missouri, 28% were born out of state, 0% were born outside of the United States and 6% were foreign born.