Mill Creek is a city located in the Washington region of the United States. During the most recent census, Mill Creek had a population of 18,244. Mill Creek is the 68th most poplulated city in the Washington region, the 2,413th most populated city in the United States and the 14,613th most populated city in the world. Mill Creek is in the America/Los Angeles timezone which is 7 hours behind UTC. Mill Creek adjusts the hour with daylight savings time during the winter months.