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Middlesex County, Massachusetts: Demographics, Geography, and Role in Greater Boston

Middlesex County, Massachusetts: demographic profile, geographic features, major towns and infrastructure, and its economic and civic role within the Greater Boston metropolitan area.

Author: Leandro Alegsa

09-04-2026

Overview

Middlesex County is a county in the Commonwealth of Massachusetts, within the United States. It lies in the eastern portion of the state and forms part of the broader Boston metropolitan area.

By a 2018 estimate the county's population was 1,614,714. That total ranked Middlesex County 22nd among U.S. counties by population and made it the largest county in both Massachusetts and New England.