# Middlesex County, Massachusetts

Middlesex County is a county located in the Commonwealth of Massachusetts, United States. As of the 2020 census, the population was 1,632,002, making it the most populous county in both Massachusetts and New England and the 22nd most populous county in the United States. This makes the county the most populous county on the East Coast outside of New York or Florida. Middlesex County is one of two U.S. counties (along with Santa Clara County, California) to be amongst the top 25 counties with the highest household income and the 25 most populated counties. It is included in the Census Bureau's Boston–Cambridge–Newton, MA–NH Metropolitan Statistical Area. As part of the 2020 United States census, the Commonwealth's mean center of population for that year was geo-centered in Middlesex County, in the town of Natick (this is not to be confused with the geographic center of Massachusetts, which is in Rutland, Worcester County).
On July 11, 1997, Massachusetts abolished the executive government of Middlesex County primarily due to the county's insolvency. Middlesex County continues to exist as a geographic boundary and is used primarily as district jurisdictions within the court system and for other administrative purposes; for example, as an election district. The National Weather Service weather alerts (such as severe thunderstorm warning) continue to localize based on Massachusetts's counties.

## History

The county was created by the Massachusetts General Court on May 10, 1643, when it was ordered that "the whole plantation within this jurisdiction be divided into four shires." Middlesex initially contained Charlestown, Cambridge, Watertown, Sudbury, Concord, Woburn, Medford, and Reading. In 1649 the first Middlesex County Registry of Deeds was created in Cambridge.
On April 19, 1775, Middlesex was the site of the first armed conflict of the American Revolutionary War.
In 1855, the Massachusetts State Legislature created a minor Registry of Deeds for the Northern District of Middlesex County in Lowell.
In the late 19th century and early 20th century, Boston annexed several of its adjacent cities and towns including Charlestown and Brighton from Middlesex County, resulting in an enlargement and accretion toward Suffolk County.
Beginning prior to the dissolution of the executive county government, the county comprised two regions with separate county seats for administrative purposes:
* The Middlesex-North District (smaller) with its county seat in Lowell under the Registry of Deeds consisted of the city of Lowell, and its adjacent towns of Billerica, Carlisle, Chelmsford, Dracut, Dunstable, Tewksbury, Tyngsborough, Westford and Wilmington.
* The Middlesex-South District (larger) with the county seat in Cambridge consisted of the remaining 44 cities and towns of Middlesex County.
Since the start of the 21st century, much of the current and former county offices have physically decentralized from the Cambridge seat, with the sole exceptions being the Registry of Deeds and the Middlesex Probate and Family Court, which both retain locations in Cambridge and Lowell. Since the first quarter of 2008, the Superior Courthouse has been seated in the city of Woburn; the Sheriff's Office is now administratively seated in the city of Medford and the Cambridge-based County Jail has since been amalgamated with another county jail facility in Billerica. The Cambridge District Court (which has jurisdiction for Arlington, Belmont and Cambridge); along with the Middlesex County District Attorney's Office, although not a part of the Middlesex County government, was also relatedly forced to relocate to Medford at the time of the closure of the Superior Courthouse building in Cambridge.

### Law and government

Of the fourteen counties of Massachusetts, Middlesex is one of eight which have had no county government or county commissioners since July 1, 1998, when county functions were assumed by state agencies at local option following a change in state law. Immediately prior to its dissolution, the executive branch consisted of three County Commissioners elected at-large to staggered four-year terms. There was a County Treasurer elected to a six-year term. The county derived its revenue primarily from document filing fees at the Registries of Deeds and from a Deeds Excise Tax; also a transfer tax was assessed on the sale price of real estate and collected by the Registries of Deeds.
Budgets as proposed by the County Commissioners were approved by a County Advisory Board that consisted of a single representative of each of the 54 cities and towns in Middlesex County. The votes of the individual members of the advisory board were weighted based on the overall valuation of property in their respective communities.
The County Sheriff and two Registers of Deeds (one for the Northern District at Lowell and another for the Southern District at Cambridge) are each elected to serve six-year terms. Besides the employees of the Sheriff's Office and the two Registries of Deeds, the county had a Maintenance Department, a Security Department, some administrative staff in the Treasurer's and Commissioners' Offices, and the employees of the hospital.
The county government also owned and operated the Superior Courthouse, one of which was formerly in Cambridge (since 2008 relocated to Woburn.) and one in Lowell; and the defunct Middlesex County Hospital in the city of Waltham.
The legislation abolishing the Middlesex County executive retained the Sheriff and Registers of Deeds as independently elected officials, and transferred the Sheriff's Office under the state Department of Public Safety and the two Registry of Deeds offices to the Massachusetts Secretary of State's Office. Additionally, all county maintenance and security employees were absorbed into the corresponding staffs of the Massachusetts Trial Court. The legislation also transferred ownership of the two Superior Courthouses to the Commonwealth of Massachusetts. The hospital was closed. Finally, the office of County Commissioner was immediately abolished and the office of County Treasurer was abolished as of December 31, 2002. Any county roads transferred to the Commonwealth as part of the dissolution. The other administrative duties (such as Sheriff, Department of Deeds and court system, etc.) and all supporting staff were transferred under the Commonwealth as well.
District attorneys of Middlesex County :
| District attorney | Term |
| Samuel Dana | 1807–1811 |
| Timothy Fuller | 1811–1812 |
| Asahel Stearns | 1813–1832 |
| Asahel Huntington | 1832–1845 |
| Albert H. Nelson | 1845–1848 |
| Charles R. Train | 1848–1851 |
| Asa W. Farr | 1851–1853 |
| Charles R. Train | 1853–1855 |
| Isaac S. Morse | 1855–1872 |
| John B. Goodrich | 1872–1874 |
| George Stevens | 1874–1879 |
| John Wilkes Hammond | 1879–1880 |
| William Burnham Stevens | 1880–1890 |
| Patrick H. Cooney | 1890–1893 |
| Fred N. Wier | 1893–1902 |
| George A. Sanderson | 1902–1907 |
| Hugh Bancroft | 1907–1908 |
| John J. Higgins | 1908–1913 |
| William J. Corcoran | 1913–1917 |
| Nathan A. Tufts | 1917–1921 |
| Endicott Peabody Saltonstall | 1921–1922 |
| Arthur Kenneth Reading | 1922–1927 |
| Robert T. Bushnell | 1927–1931 |
| Warren L. Bishop | 1931–1938 |
| William G. Andrew | 1938–1939 |
| Robert F. Bradford | 1939–1945 |
| George E. Thompson | 1945–1956 |
| Ephraim Martin | 1956–1957 |
| James O'Dea Jr. | 1957–1959 |
| John J. Droney | 1959–1983 |
| Scott Harshbarger | 1983–1991 |
| Thomas Reilly | 1991–1999 |
| Martha Coakley | 1999–2007 |
| Gerard Leone | 2007–2013 |
| Marian T. Ryan | 2013–present |
Sheriffs of Middlesex County :
| Sheriff | Term |
| Capt. Timothy Phillips | 1692–1702 |
| Capt. Samuel Gookin | 1702–1714 |
| Col. Edmund Goffe | 1714–1717 |
| Samuel Gookin$^{(2ndterm)}$ | 1717–1729 |
| Daniel Foster | 1729–1731 |
| Richard Foster, Jr. | 1731–1764 |
| Col. David Phips | 1764–1775 |
| Col. James Prescott | 1775–1781 |
| Col. Loammi Baldwin | 1781–1794 |
| Maj. Joseph Hosmer | 1794–1808 |
| Gen. William Hildreth, Jr. | 1808–1813 |
| Gen. Nathaniel Austin, Jr. | 1813–1831 |
| Benjamin Franklin Varnum | 1831–1841 |
| Col. Samuel Chandler | 1841–1851 |
| Fisher Ames Hildreth | 1851–1853 |
| John Sheppard Keyes | 1853–1859 |
| Charles Kimball | 1859–1879 |
| Eben Winslow Fiske | 1879–1883 |
| Henry Greenwood Cushing | 1883–1899 |
| John Robert Fairbain | 1899–1934 |
| Joseph M. McElroy | 1934–1947 |
| Loring R. Kew | 1947-1947 |
| Louis E. Boutwell | 1948–1949 |
| Howard W. Fitzpatrick | 1949–1970 |
| John J. Buckley | 1970–1980 |
| Edward Henneberry | 1980–1984 |
| William Quealy (acting) | 1984–1985 |
| John P. McGonigle | 1985–1994 |
| Robert C. Krekorian (acting) | 1994 |
| Anthony M. Sasso (acting) | 1994 |
| R. Bradford Bailey | 1994–1996 |
| James DiPaola | 1996–2010 |
| John Granara (Special) | 2010–2011 |
| Peter Koutoujian | 2011–Present |

### Administrative structure today

Records of land ownership in Middlesex County continue to be maintained at the two Registries of Deeds. Besides the Sheriff and the two Registers of Deeds, the Middlesex District Attorney, the Middlesex Register of Probate and the Middlesex Clerk of Courts (which were already part of state government before the abolition of Middlesex County government) are all elected countywide to six-year terms.
In Middlesex County (as in the entirety of the Commonwealth of Massachusetts), the governmental functions such as property tax assessment and collection, public education, road repair and maintenance, and elections were all conducted at the municipal city and town level and not by the county government.
In 2012 the 22-story Superior Court Building in Cambridge which was transferred from the abolished Executive County government was sold by the Commonwealth of Massachusetts. Due to its transfer from state control, many local residents had tried to force the private developers to reduce the overall height of the structure.
Even following the abolition of the executive branch for county government in Middlesex, communities are still granted a right by the Massachusetts state legislature to form their own regional compacts for sharing of services and costs thereof.

## Geography

According to the U.S. Census Bureau, the county has a total area of 847 square miles (2,190 km$^2$), of which 818 square miles (2,120 km$^2$) is land and 29 square miles (75 km$^2$) (3.5%) is water. It is the third-largest county in Massachusetts by land area.
It is bounded southeast by the Charles River and drained by the Merrimack, Nashua, and Concord rivers, and other streams.
The MetroWest region comprises much of the southern portion of the county.

### Adjacent counties

* Hillsborough County, New Hampshire (north)
* Essex County (northeast)
* Suffolk County (southeast)
* Norfolk County (south)
* Worcester County (west)

### Transportation

These routes pass through Middlesex County
* I-90, From Hopkinton to Newton
* I-93, From Somerville to Tewksbury
* I-95, From Newton to Wakefield
* I-290, In Marlboro
* I-495, From Hopkinton to Tewksbury
* US 1, From Cambridge to Malden
* US 3/Route 3, From Cambridge to Tyngsborough
* US 20, From Marlborough to Watertown
* Route 2, From Littleton to Cambridge
* Route 2A, From Shirley to Cambridge
* Route 3A, From Burlington to Tyngsborough
* Route 4, From Lexington-Arlington line to Chelmsford
* Route 9, From Framingham to Newton
* Route 13, In Townsend
* Route 16, From Holliston to Everett
* Route 27, From Sherborn to Chelmsford
* Route 28, From Cambridge to North Reading
* Route 30, From Framingham to Newton
* Route 31, In Ashby
* Route 38, From Somerville to Dracut
* Route 40, From Groton to Chelmsford
* Route 60, From Waltham to Malden
* Route 62, From Hudson to North Reading
* Route 85, From Hopkinton to Hudson
* Route 99, From Everett to Melrose
* Route 110, From Ayer to Dracut
* Route 111, From Concord to Pepperell
* Route 113, From Pepperell to Dracut
* Route 115, In Sherborn
* Route 117, From Stow to Waltham
* Route 119, From Concord to Ashby
* Route 125, From Wilmington to North Reading
* Route 126, From Holliston to Concord
* Route 128, From Newton to Wakefield
* Route 129, From Chelmsford to Wakefield
* Route 133, From Lowell to Tewksbury
* Route 135, From Hopkinton to Natick
* Route 225, From Shirley to Lexington

### National protected areas

* Assabet River National Wildlife Refuge
* Great Meadows National Wildlife Refuge
* Longfellow House–Washington's Headquarters National Historic Site
* Lowell National Historical Park
* Minute Man National Historical Park
* Oxbow National Wildlife Refuge (part)

## Demographics

As of 2006, Middlesex County was tenth in the United States on the list of most millionaires per county.
As of the 2010 United States census, there were 1,503,085 people, 580,688 households, and 366,656 families residing in the county. The population density was 1,837.9 inhabitants per square mile (709.6/km$^2$). There were 612,004 housing units at an average density of 748.3 per square mile (288.9/km$^2$). The racial makeup of the county was 80.0% white, 9.3% Asian, 4.7% black or African American, 0.2% American Indian, 3.3% from other races, and 2.5% from two or more races. Those of Hispanic or Latino origin made up 6.5% of the population.
The largest ancestry groups were:
* 23.5% Irish
* 16.2% Italian
* 11.2% English
* 7.1% German
* 5.6% French
* 4.0% Polish
* 3.6% French Canadian
* 3.2% Chinese
* 3.1% Portuguese
* 2.9% American
* 2.7% Scottish
* 2.6% Russian
* 2.5% Indian
* 2.4% Brazilian
* 2.0% Scotch-Irish
* 2.0% Puerto Rican
* 1.7% Swedish
* 1.6% Greek
* 1.2% Sub-Saharan African
* 1.2% Haitian
* 1.2% Armenian
* 1.1% Canadian
* 1.0% Cambodian
* 1.0% Arab
Of the 580,688 households, 31.0% had children under the age of 18 living with them, 49.5% were married couples living together, 10.1% had a female householder with no husband present, 36.9% were non-families, and 27.8% of all households were made up of individuals. The average household size was 2.49 and the average family size was 3.10. The median age was 38.5 years.
The median income for a household in the county was $77,377 and the median income for a family was $97,382. Males had a median income of $64,722 versus $50,538 for females. The per capita income for the county was $40,139. About 5.1% of families and 7.6% of the population were below the poverty line, including 8.0% of those under age 18 and 8.0% of those age 65 or over.
79.6% spoke English, 4.3% Spanish, 2.7% Portuguese, 1.6% Italian, 1.6% Chinese including Mandarin and other Chinese dialects and 1.5% French as their first language.
Middlesex County has the largest Irish-American population of any U.S. county with a plurality of Irish ancestry.

### Demographic breakdown by town
#### Income

The ranking of unincorporated communities that are included on the list is reflective if the census-designated locations and villages were included as cities or towns. Data is from the 2007-2011 American Community Survey 5-Year Estimates.
| Rank | Town | | Per capita income | Median household income | Median family income | Population | Number of households |
| 1 | Weston | Town | $96,475 | $180,815 | $220,441 | 11,229 | 3,557 |
| 2 | Sherborn | Town | $70,983 | $152,083 | $183,456 | 4,102 | 1,463 |
| 3 | Wayland | Town | $70,185 | $125,076 | $151,812 | 12,939 | 4,902 |
| 4 | Carlisle | Town | $68,060 | $159,063 | $171,167 | 4,814 | 1,612 |
| 5 | Lexington | Town | $67,584 | $136,610 | $158,888 | 31,129 | 11,411 |
| 6 | Concord | Town | $67,374 | $127,951 | $156,352 | 17,523 | 6,197 |
| 7 | Winchester | Town | $65,172 | $127,665 | $160,706 | 21,205 | 7,611 |
| 8 | Sudbury | Town | $63,862 | $159,713 | $173,587 | 17,482 | 5,613 |
| 9 | Newton | City | $60,323 | $109,724 | $141,944 | 84,583 | 30,735 |
| 10 | Lincoln | Town | $57,471 | $130,523 | $141,667 | 6,480 | 2,150 |
| 11 | Hopkinton | Town | $56,939 | $126,350 | $149,213 | 14,691 | 4,893 |
| | Chestnut Hill (02467) | ZCTA | $55,947 | $114,140 | $151,375 | 21,952 | 6,237 |
| 12 | Belmont | Town | $54,361 | $99,529 | $121,250 | 24,548 | 9,465 |
| | Cochituate | CDP | $52,936 | $107,589 | $133,082 | 6,384 | 2,496 |
| 13 | Boxborough | Town | $51,159 | $103,918 | $134,583 | 4,957 | 1,984 |
| 14 | Acton | Town | $49,603 | $109,491 | $135,000 | 21,656 | 7,924 |
| 15 | Natick | Town | $49,012 | $90,046 | $117,259 | 32,729 | 13,440 |
| 16 | Bedford | Town | $48,899 | $101,886 | $128,448 | 13,192 | 4,951 |
| 17 | Stow | Town | $48,448 | $112,130 | $132,061 | 6,488 | 2,328 |
| | West Concord | CDP | $47,633 | $103,693 | $145,242 | 6,134 | 2,069 |
| 18 | Holliston | Town | $47,624 | $107,374 | $125,236 | 13,512 | 4,918 |
| 19 | Westford | Town | $47,587 | $119,511 | $135,000 | 21,716 | 7,308 |
| 20 | Arlington | Town | $47,571 | $85,059 | $107,862 | 42,570 | 19,007 |
| 21 | Groton | Town | $47,003 | $117,903 | $135,143 | 10,478 | 3,650 |
| 22 | Ashland | Town | $46,626 | $93,770 | $116,799 | 16,305 | 6,484 |
| 23 | Cambridge | City | $46,242 | $69,017 | $94,536 | 104,322 | 45,386 |
| 24 | Reading | Town | $44,949 | $99,131 | $117,477 | 24,504 | 9,055 |
| 25 | Chelmsford | Town | $42,535 | $90,895 | $110,967 | 33,610 | 13,304 |
| 26 | North Reading | Town | $42,256 | $104,069 | $116,729 | 14,703 | 5,077 |
| 27 | Dunstable | Town | $41,937 | $109,205 | $121,406 | 3,128 | 1,087 |
| 28 | Littleton | Town | $41,815 | $103,438 | $114,094 | 8,810 | 3,198 |
| | Middlesex County | County | $41,453 | $79,691 | $100,267 | 1,491,762 | 577,349 |
| 29 | Watertown | City | $41,090 | $76,718 | $90,521 | 31,792 | 14,042 |
| 30 | Wakefield | Town | $40,227 | $85,379 | $112,293 | 24,794 | 10,058 |
| 31 | Burlington | Town | $40,083 | $92,236 | $107,339 | 24,207 | 9,177 |
| 32 | Melrose | City | $39,873 | $84,599 | $105,893 | 26,864 | 10,963 |
| | Groton | CDP | $39,208 | $55,446 | $127,708 | 1,077 | 507 |
| | Hopkinton | CDP | $38,507 | $71,536 | $105,882 | 2,110 | 877 |
| 33 | Tyngsborough | Town | $38,067 | $101,103 | $111,780 | 11,198 | 3,797 |
| 34 | Stoneham | Town | $37,573 | $77,476 | $95,490 | 21,413 | 8,909 |
| 35 | Marlborough | City | $37,314 | $72,853 | $94,770 | 38,087 | 15,856 |
| 36 | Wilmington | Town | $37,084 | $100,861 | $107,436 | 22,116 | 7,200 |
| 37 | Pepperell | Town | $37,081 | $84,618 | $102,946 | 11,407 | 4,125 |
| 38 | Maynard | Town | $36,818 | $77,255 | $93,116 | 10,083 | 4,222 |
| 39 | Tewksbury | Town | $36,509 | $86,378 | $103,008 | 28,778 | 10,670 |
| 40 | Hudson | Town | $36,141 | $76,714 | $95,746 | 18,845 | 7,679 |
| | Pepperell | CDP | $35,227 | $68,500 | $65,417 | 2,239 | 852 |
| | Massachusetts | State | $35,051 | $65,981 | $83,371 | 6,512,227 | 2,522,409 |
| 41 | Medford | City | $34,615 | $72,033 | $83,078 | 55,843 | 22,461 |
| | Hudson | CDP | $33,734 | $68,812 | $86,216 | 14,797 | 6,129 |
| 42 | Woburn | City | $33,725 | $72,540 | $87,924 | 37,831 | 15,357 |
| 43 | Waltham | City | $33,717 | $68,326 | $82,233 | 60,209 | 23,520 |
| 44 | Framingham | City | $33,665 | $66,047 | $86,977 | 67,844 | 26,167 |
| | Pinehurst | CDP | $33,572 | $95,038 | $100,650 | 7,289 | 2,414 |
| 45 | Billerica | Town | $33,347 | $88,531 | $98,371 | 39,930 | 13,859 |
| 46 | Somerville | City | $32,785 | $64,480 | $71,518 | 75,566 | 31,476 |
| 47 | Ashby | Town | $32,434 | $82,614 | $84,655 | 3,030 | 1,060 |
| 48 | Ayer | Town | $32,179 | $54,899 | $78,947 | 7,370 | 3,063 |
| | Littleton Common | CDP | $32,058 | $80,352 | $105,217 | 2,907 | 1,131 |
| 49 | Dracut | Town | $31,533 | $71,824 | $88,281 | 29,249 | 11,173 |
| 50 | Townsend | Town | $31,201 | $76,250 | $91,023 | 8,906 | 3,114 |
| | East Pepperell | CDP | $30,475 | $74,077 | $79,104 | 2,195 | 811 |
| | Ayer | CDP | $30,456 | $42,055 | $79,708 | 2,573 | 1,205 |
| | United States | Country | $27,915 | $52,762 | $64,293 | 306,603,772 | 114,761,359 |
| | Townsend | CDP | $27,166 | $51,512 | $71,023 | 968 | 453 |
| 51 | Malden | City | $26,893 | $52,842 | $65,763 | 58,821 | 23,422 |
| | Shirley | CDP | $24,943 | $41,250 | $41,838 | 1,330 | 593 |
| 52 | Everett | City | $24,575 | $48,319 | $58,045 | 41,079 | 15,681 |
| 53 | Shirley | Town | $24,427 | $71,146 | $78,493 | 7,235 | 2,189 |
| 54 | Lowell | City | $23,600 | $51,471 | $57,934 | 105,860 | 39,399 |
| | Devens | CDP | $13,933 | $72,986 | $73,194 | 1,704 | 113 |

## Law enforcement

The primary responsibility of the Middlesex Sheriff's Office is oversight of the Middlesex House of Correction and Jail in Billerica. It formerly ran the Middlesex Jail in Cambridge, which closed on June 28, 2014. In addition, the Sheriff's Office operates the Office of Civil Process and, the Lowell Community Counseling Centers, and crime prevention and community service programs. The office of sheriff was created in 1692, making it one of the oldest law enforcement agencies in the United States. The sheriff is elected to a 6-year term.
Notable sheriffs include:
* Col. James Prescott (1775–1781)
* Col. Loammi Baldwin (1781–1794)
* Col. Samuel Chandler (1841–1851)
* Charles Kimball (1859–1879)
* John J. Buckley (1970–1980)
* John P. McGonigle (1985–1994)
* James DiPaola (1996–2010)
* John Granara (Special) (2010–2011)
* Peter Koutoujian (2011–Present)

## Politics

Voter registration and party enrollment as of August 2024 :
| | Unenrolled | 712,349 | 62.46% |
| | Democratic | 327,852 | 29.07% |
| | Republican | 77,758 | 6.9% |
| | Libertarian | 3,095 | 0.27% |
| | Other parties | 6,641 | 0.59% |
| Total | Total | 1,127,675 | 100% |
Prior to 1960, Middlesex County was a Republican Party stronghold, backing only two Democratic Party presidential candidates from 1876 to 1956. The 1960 election started a reverse trend, with the county becoming a Democratic stronghold. This has been even more apparent in recent years, with George H. W. Bush in 1988 being the last Republican presidential candidate to manage forty percent of the county's votes and Mitt Romney in 2012 being the last Republican presidential candidate to manage even thirty percent of the vote. In 2020, Joe Biden won 71% of the vote, the highest percent for any presidential candidate since 1964.
United States presidential election results for Middlesex County, Massachusetts :
| Year | Republican | Republican | Democratic | Democratic | Third party(ies) | Third party(ies) |
| Year | No. | % | No. | % | No. | % |
| 2024 | 235,118 | 28.85% | 554,471 | 68.05% | 25,243 | 3.10% |
| 2020 | 226,956 | 26.28% | 617,196 | 71.47% | 19,425 | 2.25% |
| 2016 | 219,793 | 27.59% | 520,360 | 65.31% | 56,582 | 7.10% |
| 2012 | 267,321 | 35.45% | 471,804 | 62.56% | 15,045 | 1.99% |
| 2008 | 245,766 | 33.85% | 464,484 | 63.98% | 15,781 | 2.17% |
| 2004 | 237,815 | 34.52% | 440,862 | 63.99% | 10,283 | 1.49% |
| 2000 | 198,914 | 30.27% | 404,043 | 61.49% | 54,091 | 8.23% |
| 1996 | 169,926 | 27.06% | 398,190 | 63.41% | 59,861 | 9.53% |
| 1992 | 193,703 | 28.10% | 343,994 | 49.89% | 151,756 | 22.01% |
| 1988 | 290,352 | 43.82% | 361,563 | 54.57% | 10,713 | 1.62% |
| 1984 | 319,604 | 49.42% | 325,065 | 50.26% | 2,085 | 0.32% |
| 1980 | 256,999 | 40.30% | 270,751 | 42.46% | 109,929 | 17.24% |
| 1976 | 260,044 | 40.42% | 359,919 | 55.94% | 23,419 | 3.64% |
| 1972 | 269,064 | 43.56% | 345,343 | 55.91% | 3,244 | 0.53% |
| 1968 | 188,304 | 32.60% | 370,310 | 64.11% | 18,982 | 3.29% |
| 1964 | 134,729 | 23.36% | 439,790 | 76.25% | 2,291 | 0.40% |
| 1960 | 246,126 | 40.78% | 356,130 | 59.01% | 1,260 | 0.21% |
| 1956 | 343,125 | 61.12% | 216,668 | 38.60% | 1,580 | 0.28% |
| 1952 | 316,069 | 56.99% | 236,910 | 42.72% | 1,626 | 0.29% |
| 1948 | 228,262 | 46.98% | 248,240 | 51.09% | 9,406 | 1.94% |
| 1944 | 236,102 | 52.81% | 210,253 | 47.03% | 725 | 0.16% |
| 1940 | 242,658 | 52.36% | 218,663 | 47.18% | 2,116 | 0.46% |
| 1936 | 199,704 | 47.60% | 189,512 | 45.17% | 30,304 | 7.22% |
| 1932 | 184,486 | 50.44% | 174,257 | 47.64% | 7,008 | 1.92% |
| 1928 | 189,189 | 52.00% | 173,339 | 47.64% | 1,313 | 0.36% |
| 1924 | 162,530 | 63.68% | 64,544 | 25.29% | 28,161 | 11.03% |
| 1920 | 156,636 | 69.90% | 61,661 | 27.52% | 5,781 | 2.58% |
| 1916 | 60,802 | 53.77% | 49,844 | 44.08% | 2,426 | 2.15% |
| 1912 | 30,511 | 29.66% | 36,689 | 35.67% | 35,667 | 34.67% |
| 1908 | 58,672 | 61.19% | 31,362 | 32.71% | 5,853 | 6.10% |
| 1904 | 55,704 | 60.63% | 32,889 | 35.80% | 3,275 | 3.56% |
| 1900 | 49,638 | 60.57% | 29,476 | 35.97% | 2,841 | 3.47% |
| 1896 | 57,281 | 71.36% | 19,591 | 24.41% | 3,394 | 4.23% |
| 1892 | 40,375 | 52.37% | 34,769 | 45.10% | 1,946 | 2.52% |
| 1888 | 35,768 | 54.31% | 28,570 | 43.38% | 1,519 | 2.31% |
| 1884 | 27,654 | 48.50% | 22,206 | 38.95% | 7,157 | 12.55% |
| 1880 | 30,339 | 59.31% | 19,801 | 38.71% | 1,013 | 1.98% |
| 1876 | 27,304 | 58.02% | 19,561 | 41.57% | 193 | 0.41% |
| 1872 | 26,570 | 68.12% | 12,434 | 31.88% | 0 | 0.00% |
| 1868 | 24,694 | 66.47% | 12,454 | 33.53% | 0 | 0.00% |

## Communities

Most municipalities in Middlesex County have a town form of government; the remainder are cities, and are so designated on this list. Villages listed below are census or postal divisions but have no separate corporate or statutory existence from the cities and towns in which they are located.

### Cities

* Cambridge (traditional county seat) de jure
* Everett
* Framingham
* Lowell (traditional county seat)
* Malden
* Marlborough
* Medford
* Melrose
* Newton
* Somerville
* Waltham
* Watertown
* Woburn

### Towns

* Acton
* Arlington
* Ashby
* Ashland
* Ayer
* Bedford
* Belmont
* Billerica
* Boxborough
* Burlington
* Carlisle
* Chelmsford
* Concord
* Dracut
* Dunstable
* Groton
* Holliston
* Hopkinton
* Hudson
* Lexington
* Lincoln
* Littleton
* Maynard
* Natick
* North Reading
* Pepperell
* Reading
* Sherborn
* Shirley
* Stoneham
* Stow
* Sudbury
* Tewksbury
* Townsend
* Tyngsborough
* Wakefield
* Wayland
* Westford
* Weston
* Wilmington
* Winchester

### Census-designated places

* Ayer
* Cochituate
* Devens
* East Pepperell
* Groton
* Hanscom AFB
* Hopkinton
* Littleton Common
* Pepperell
* Pinehurst
* Shirley
* Townsend
* West Concord

### Other villages and neighborhoods

* Auburndale
* Chestnut Hill
* East Lexington
* Felchville
* Forge Village
* Gleasondale
* Graniteville
* Greenwood
* Melrose Highlands
* Nabnasset
* Newton Centre
* Newton Highlands
* Newton Lower Falls
* Newton Upper Falls
* Newtonville
* Nonantum
* North Billerica
* North Chelmsford
* North Woburn
* Pingryville
* Saxonville
* Thompsonville
* Waban
* West Newton

## Education

School districts include:
K-12:
* Ayer-Shirley School District
* Acton-Boxborough Regional School District
* Arlington School District
* Ashland School District
* Bedford School District
* Belmont School District
* Billerica School District
* Burlington School District
* Cambridge Public School District
* Chelmsford School District
* Dracut School District
* Everett School District
* Framingham School District
* Groton-Dunstable School District
* Holliston School District
* Hopkinton School District
* Hudson School District
* Lexington School District
* Littleton School District
* Lowell Public Schools
* Malden School District
* Marlborough School District
* Maynard School District
* Medford Public Schools
* Melrose School District
* Nashoba School District
* Natick School District
* Newton School District
* North Middlesex School District
* North Reading School District
* Reading Public Schools
* Somerville School District
* Stoneham School District
* Tewksbury School District
* Tyngsborough School District
* Wakefield School District
* Waltham School District
* Watertown School District
* Wayland School District
* Westford School District
* Weston School District
* Wilmington School District
* Winchester School District
* Woburn School District
Secondary:
* Concord-Carlisle School District
* Dover-Sherborn School District
* Lincoln-Sudbury School District
Elementary:
* Carlisle School District
* Concord School District
* Lincoln School District
* Sherborn School District
* Sudbury School District
Tertiary institutions include:
* Harvard University (Cambridge)
* Massachusetts Institute of Technology (MIT) (Cambridge)
* Framingham State University (Framingham)

## Culture

Middlesex County is home to the Middlesex County Volunteers, a fife and drum corps that plays music from the 17th, 18th, 19th and 20th centuries. Founded in 1982 at the end of the United States Bicentennial celebration, the group performs extensively throughout New England. They have also performed at the Boston Pops, throughout the British Isles and Western Europe, and at the Edinburgh Military Tattoo's Salute to Australia in Sydney, Australia.