Marlborough is a city located in Middlesex County Massachusetts. With a 2020 population of 39,359, it is the 36th largest city in Massachusetts and the 1001st largest city in the United States . Marlborough is currently declining at a rate of -0.30% annually but its population has increased by 2.23% since the most recent census, which recorded a population of 38,499 in 2010. Marlborough reached it's highest population of 39,797 in 2015. Spanning over 22 miles, Marlborough has a population density of 1,887 people per square mile.
The average household income in Marlborough is $102,739 with a poverty rate of 5.64%. The median rental costs in recent years comes to $1,482 per month, and the median house value is $348,500. The median age in Marlborough is 39.8 years, 38.8 years for males, and 41.1 years for females.