Mill Creek is a city located in Washington. With a 2020 population of 20,737, it is the 56th largest city in Washington and the 1798th largest city in the United States. Mill Creek is currently declining at a rate of -0.38% annually but its population has increased by 13.66% since the most recent census, which recorded a population of 18,244 in 2010. Mill Creek reached it's highest population of 20,977 in 2018. Spanning over 5 miles, Mill Creek has a population density of 4,466 people per square mile.
The average household income in Mill Creek is $128,291 with a poverty rate of 4.34%. The median rental costs in recent years comes to $1,812 per month, and the median house value is $536,800. The median age in Mill Creek is 38.3 years, 37.5 years for males, and 39.2 years for females. For every 100 females there are 88.9 males.