| ZIP Codes: | 108 ZIP Codes (83 Standard, 20 PO Box, 5 Unique) [See All] |
| Area Codes: | 339 / 351 / 508 / 617 / 774 / 781 / 857 / 978 |
| Timezone: | Eastern (GMT -05:00) |
| Local Time: | 2:12:27 PM |
| Population: | 1,653,842 [See All] |
| FIPS: | 25017 |
| CBSA: | Boston-Cambridge-Newton, MA-NH |
| Land Area: | 855 sq mi |
| Water Area: | 29 sq mi |
| Coordinates: | 42.4514, -71.2935 |
| Quick Link: |
1,653,842 residents live across 108 ZIPs covering 855 sq mi, served by 78 distinct USPS-recognized cities.
Population moved from 1,554,835 to 1,653,842 from 2014 to 2024 — a +6.4% change. 68 ZIPs gained residents, 15 lost.
The county's wealthiest ZIP 02493 (Weston, $250,001 median) and poorest ZIP 01850 (Lowell, $69,780) are 20.5 miles apart — a 3.6× income gap across local geography.
Median home values vary 5.0× across this county — from $390,500 in 01431 (Ashby) to $1,954,500 in 02142 (Cambridge).
Density varies 185× across the county — from 134 people/sq mi in 01431 (Ashby) to 24,695 in 02139 (Cambridge).
Educational attainment ranges from 19.8% bachelor's+ in 01434 (Devens) to 89.4% in 02468 (Waban) — the breadth of educational profiles across the area.
Within Massachusetts, this is the #1 most populous of 14 counties and ranks #2 for median household income with the #8 fastest decade growth .
On the national stage, Middlesex County is the #21 most populous US county , ranks #21 for income .
Hosts 4 single-entity Unique ZIPs: 01889Massachusetts District ; 02477Field Premium Inc ; 01813Mellon Financial Services ; and 01805Lahey Clinic Med Ctr .
Weighted by population, the typical household earns about $139,540 across the county — reflecting what a typical resident sees, not a simple ZIP average.
59.6% of adults age 25+ hold a bachelor's degree or higher (696,664 of 1,168,805 reporting).
83 Standard delivery, 20 PO Box only, 5 single-entity Unique ZIPs serve this county.
46 ZIPs in this county where more than 60% of adults 25+ hold a bachelor's degree — typically college campuses, research enclaves, or tech corridors.
5 ZIP codes in this county serve a single facility — typically theme parks, universities, large corporations, airports, or government complexes.
Median household income spans 3.6× between the wealthiest and poorest ZIPs — a sign of significant intra-county inequality.
| ZIP | City | Type | Population | Median Income | Area (sq mi) | 10-yr Growth |
|---|---|---|---|---|---|---|
| 02148 | Malden | Standard | 65,906 | $100,606 | 5.1 | 9.3% |
| 02155 | Medford | Standard | 61,730 | $129,700 | 8.8 | 4.3% |
| 02149 | Everett | Standard | 50,045 | $85,218 | 3.7 | 17.2% |
| 01801 | Woburn | Standard | 41,939 | $111,185 | 12.9 | 6.7% |
| 01752 | Marlborough | Standard | 41,647 | $91,968 | 22.3 | 6.4% |
| 02139 | Cambridge | Standard | 40,033 | $134,586 | 1.6 | 11.9% |
| 01702 | Framingham | Standard | 39,789 | $82,496 | 8.9 | 4.2% |
| 02138 | Cambridge | Standard | 38,509 | $119,967 | 3.1 | 4.3% |
| 01852 | Lowell | Standard | 37,144 | $80,906 | 5.3 | 13.5% |
| 01760 | Natick | Standard | 36,782 | $138,563 | 15.8 | 8.0% |
| 02472 | Watertown | Standard | 35,620 | $126,336 | 4.1 | 8.1% |
| 01851 | Lowell | Standard | 33,403 | $92,401 | 3.5 | 10.0% |
| 01826 | Dracut | Standard | 32,629 | $114,196 | 21.5 | 7.6% |
| 01701 | Framingham | Standard | 32,618 | $137,094 | 17.6 | 2.6% |
| 02453 | Waltham | Standard | 31,591 | $115,366 | 3.8 | 9.1% |
| 01876 | Tewksbury | Standard | 31,004 | $130,204 | 21.3 | 6.5% |
| 01821 | Billerica | Standard | 30,143 | $149,042 | 17.1 | -3.3% |
| 01854 | Lowell | Standard | 30,081 | $72,709 | 4.5 | 3.0% |
| 02176 | Melrose | Standard | 29,650 | $133,953 | 4.8 | 7.8% |
| 02474 | Arlington | Standard | 28,642 | $150,560 | 3.3 | 5.6% |
| 01880 | Wakefield | Standard | 27,793 | $134,306 | 7.9 | 9.2% |
| 02145 | Somerville | Standard | 27,495 | $123,755 | 1.4 | 10.8% |
| 02478 | Belmont | Standard | 27,175 | $183,137 | 4.7 | 8.2% |
| 01824 | Chelmsford | Standard | 26,650 | $140,050 | 18.3 | 4.2% |
| 01803 | Burlington | Standard | 26,274 | $146,436 | 11.8 | 4.3% |
| 01867 | Reading | Standard | 25,612 | $165,912 | 10.1 | 3.7% |
| 02143 | Somerville | Standard | 25,513 | $130,753 | 1.5 | -1.6% |
| 02144 | Somerville | Standard | 25,448 | $150,313 | 1.1 | 3.7% |
| 01886 | Westford | Standard | 24,690 | $187,198 | 31.4 | 8.0% |
| 01720 | Acton | Standard | 23,526 | $159,010 | 20.1 | 6.0% |
| 01890 | Winchester | Standard | 23,406 | $230,198 | 6.3 | 7.1% |
| 02180 | Stoneham | Standard | 23,355 | $113,964 | 6.7 | 8.1% |
| 01887 | Wilmington | Standard | 23,336 | $168,152 | 17.1 | 1.9% |
| 02467 | Chestnut Hill | Standard | 23,001 | $169,104 | 4.9 | -3.0% |
| 02140 | Cambridge | Standard | 21,204 | $135,286 | 1.2 | 18.5% |
| 01749 | Hudson | Standard | 20,077 | $103,400 | 11.9 | 3.1% |
| 01748 | Hopkinton | Standard | 19,358 | $222,801 | 27.9 | 24.1% |
| 01776 | Sudbury | Standard | 19,270 | $236,509 | 25.2 | 5.9% |
| 01721 | Ashland | Standard | 18,873 | $127,539 | 12.9 | 11.1% |
| 02459 | Newton Center | Standard | 18,449 | $227,594 | 6.0 | -0.4% |
| 01742 | Concord | Standard | 18,448 | $195,125 | 25.7 | -2.6% |
| 02421 | Lexington | Standard | 18,080 | $227,813 | 9.3 | -1.5% |
| 01850 | Lowell | Standard | 17,740 | $69,780 | 1.5 | 9.5% |
| 02476 | Arlington | Standard | 17,708 | $151,131 | 2.2 | 6.6% |
| 02451 | Waltham | Standard | 17,393 | $122,335 | 6.3 | -0.3% |
| 02420 | Lexington | Standard | 16,215 | $245,031 | 6.9 | 16.3% |
| 02452 | Waltham | Standard | 15,808 | $118,431 | 3.9 | 2.0% |
| 01864 | North Reading | Standard | 15,765 | $147,768 | 13.5 | 3.4% |
| 01746 | Holliston | Standard | 15,094 | $159,817 | 18.8 | 7.8% |
| 01730 | Bedford | Standard | 14,707 | $172,400 | 13.8 | 7.3% |
| 02141 | Cambridge | Standard | 14,517 | $126,522 | 0.6 | 8.8% |
| 01778 | Wayland | Standard | 14,033 | $219,375 | 16.0 | 4.6% |
| 02458 | Newton | Standard | 13,050 | $153,520 | 2.0 | 7.9% |
| 01879 | Tyngsboro | Standard | 12,550 | $129,348 | 18.0 | 5.8% |
| 01862 | North Billerica | Standard | 12,129 | $138,571 | 9.3 | 11.2% |
| 02465 | West Newton | Standard | 11,697 | $194,265 | 2.1 | 1.7% |
| 01463 | Pepperell | Standard | 11,697 | $123,911 | 23.2 | -0.7% |
| 02493 | Weston | Standard | 11,579 | $250,001 | 17.3 | -1.1% |
| 01450 | Groton | Standard | 11,356 | $193,292 | 33.8 | 3.3% |
| 01754 | Maynard | Standard | 10,712 | $124,067 | 4.9 | 3.9% |
| 01460 | Littleton | Standard | 10,280 | $149,722 | 17.8 | 12.3% |
| 02460 | Newtonville | Standard | 10,099 | $177,837 | 1.3 | 5.3% |
| 01863 | North Chelmsford | Standard | 9,796 | $144,875 | 4.7 | 9.9% |
| 02466 | Auburndale | Standard | 8,679 | $170,089 | 1.7 | -3.3% |
| 01432 | Ayer | Standard | 8,521 | $101,966 | 7.5 | 16.1% |
| 01775 | Stow | Standard | 7,165 | $185,809 | 17.9 | 4.7% |
| 01464 | Shirley | Standard | 6,976 | $122,365 | 16.3 | -5.8% |
| 02461 | Newton Highlands | Standard | 6,975 | $224,000 | 1.4 | -1.7% |
| 01469 | Townsend | Standard | 6,820 | $103,801 | 21.8 | -6.9% |
| 02468 | Waban | Standard | 5,773 | $250,001 | 1.5 | 7.4% |
| 01719 | Boxborough | Standard | 5,496 | $144,611 | 9.6 | 7.7% |
| 01741 | Carlisle | Standard | 5,239 | $250,001 | 15.5 | 5.5% |
| 01773 | Lincoln | Standard | 4,891 | $209,327 | 14.4 | -8.9% |
| 02142 | Cambridge | Standard | 4,737 | $147,723 | 0.8 | 56.3% |
| 01770 | Sherborn | Standard | 4,427 | $250,001 | 16.3 | 5.4% |
| 02464 | Newton Upper Falls | Standard | 3,833 | $105,729 | 0.6 | 33.6% |
| 01827 | Dunstable | Standard | 3,408 | $208,512 | 16.8 | 3.3% |
| 01431 | Ashby | Standard | 3,211 | $115,598 | 24.0 | 2.0% |
| 01474 | West Townsend | Standard | 2,280 | $136,371 | 11.1 | 22.9% |
| 01731 | Hanscom Afb | Standard | 2,110 | $104,688 | 1.2 | 11.5% |
| 01434 | Devens | Standard | 1,564 | $162,143 | 5.8 | -5.6% |
| 02462 | Newton Lower Falls | Standard | 1,470 | $216,339 | 0.8 | 12.6% |
| 01718 | Acton | Standard | 404 | $104,167 | 0.1 | 33.3% |
| 02471 | Watertown | PO Box | — | — | 0.0 | — |
| 01888 | Woburn | PO Box | — | — | 0.0 | — |
| 02477 | Watertown | Unique | — | — | 0.0 | — |
| 02153 | Medford | PO Box | — | — | 0.0 | — |
| 01813 | Woburn | Unique | — | — | 0.0 | — |
| 02456 | New Town | PO Box | — | — | 0.0 | — |
| 01703 | Framingham | PO Box | — | — | 0.0 | — |
| 01822 | Billerica | PO Box | — | — | 0.0 | — |
| 02475 | Arlington Heights | PO Box | — | — | 0.0 | — |
| 02454 | Waltham | PO Box | — | — | 0.0 | — |
| 02479 | Waverley | PO Box | — | — | 0.0 | — |
| 02156 | West Medford | PO Box | — | — | 0.0 | — |
| 01805 | Burlington | Unique | — | — | 0.0 | — |
| 02238 | Cambridge | PO Box | — | — | 0.0 | — |
| 01472 | West Groton | PO Box | — | — | 0.0 | — |
| 02495 | Nonantum | PO Box | — | — | 0.0 | — |
| 01865 | Nutting Lake | PO Box | — | — | 0.0 | — |
| 01866 | Pinehurst | PO Box | — | — | 0.0 | — |
| 01853 | Lowell | PO Box | — | — | 0.0 | — |
| 01705 | Framingham | PO Box | — | — | 0.0 | — |
| 01704 | Framingham | PO Box | — | — | 0.0 | — |
| 01889 | North Reading | Unique | — | — | 0.0 | — |
| 01815 | Woburn | Unique | — | — | 0.0 | — |
| 01784 | Woodville | PO Box | — | — | 0.0 | — |
| 02455 | North Waltham | PO Box | — | — | 0.0 | — |