Middlesex County, Massachusetts
Massachusetts's location within the U.S.
|Founded||May 10, 1643|
|Seat||Lowell and Cambridge|
|• Total||847 sq mi (2,190 km2)|
|• Land||818 sq mi (2,120 km2)|
|• Water||29 sq mi (80 km2) 3.5%%|
| • Estimate |
|• Density||1,838/sq mi (710/km2)|
|Time zone||UTC−5 (Eastern)|
|• Summer (DST)||UTC−4 (EDT)|
|Congressional districts||3rd, 4th, 5th, 6th, 7th|
Middlesex County is a county in the Commonwealth of Massachusetts, in the United States. As of 2018, the population was 1,614,714, making it the 22nd most populous county in the United States. It is the most populous county in both Massachusetts and New England.