Millwood, WA has a population of 1,655 and is the 12,124th largest city in the United States. The population density is 2,378 per sq mi which is 2360% higher than the Washington average and 2525% higher than the national average. The median age in Millwood is 41 which is approximately 9% higher than the Washington average of 38. In Millwood, 55% of the population over 15 years of age are married, 97% speak English and 1% speak Spanish. 58% of Millwood residents were born in Washington, 39% were born out of state, 1% were born outside of the United States and 1% were foreign born.