
Middlesex County
- State:
- Massachusetts
Middlesex County's estimated 2025 population is 1,638,268 with a growth rate of 0.44% in the past year according to the most recent United States census data. Middlesex County is the 1st largest county in Massachusetts. The 2010 population was 1,507,694 and has seen a growth of 8.66% since that time.