Potomac is a city located in the Maryland region of the United States. During the most recent census, Potomac had a population of 44,965. Potomac is the 19th most poplulated city in the Maryland region, the 924th most populated city in the United States and the 7,509th most populated city in the world. Potomac is in the America/New York timezone which is 4 hours behind UTC. Potomac adjusts the hour with daylight savings time during the winter months.