81 zips
| Zip Code | City | Population ↓ |
|---|---|---|
| 2148 | Malden | 65,463 |
| 2155 | Medford | 63,873 |
| 2149 | Everett | 48,685 |
| 1752 | Marlborough | 41,391 |
| 1801 | Woburn | 40,992 |
| 2139 | Cambridge | 39,856 |
| 1702 | Framingham | 38,898 |
| 2138 | Cambridge | 38,006 |
| 1852 | Lowell | 36,546 |
| 1760 | Natick | 36,274 |
| 2472 | Watertown | 35,300 |
| 1701 | Framingham | 32,973 |
| 1851 | Lowell | 32,323 |
| 1826 | Dracut | 32,309 |
| 1821 | Billerica | 30,854 |
| 1876 | Tewksbury | 30,817 |
| 2453 | Waltham | 30,365 |
| 2176 | Melrose | 29,477 |
| 1854 | Lowell | 29,062 |
| 2474 | Arlington | 28,167 |
| 2145 | Somerville | 27,692 |
| 1880 | Wakefield | 27,026 |
| 2478 | Belmont | 26,964 |
| 1824 | Chelmsford | 26,612 |
| 1803 | Burlington | 26,004 |
| 1867 | Reading | 25,443 |
| 2143 | Somerville | 25,329 |
| 2144 | Somerville | 25,022 |
| 1886 | Westford | 24,524 |
| 1887 | Wilmington | 23,191 |
| 1720 | Acton | 23,081 |
| 2180 | Stoneham | 22,992 |
| 1890 | Winchester | 22,809 |
| 2140 | Cambridge | 21,553 |
| 1749 | Hudson | 19,947 |
| 2459 | Newton Center | 19,182 |
| 1776 | Sudbury | 18,926 |
| 1748 | Hopkinton | 18,748 |
| 1721 | Ashland | 18,634 |
| 2451 | Waltham | 18,379 |
| 1742 | Concord | 18,311 |
| 2421 | Lexington | 17,865 |
| 2476 | Arlington | 17,739 |
| 1850 | Lowell | 16,806 |
| 2420 | Lexington | 16,356 |
| 2452 | Waltham | 15,830 |
| 1864 | North Reading | 15,529 |
| 1746 | Holliston | 14,902 |
| 1730 | Bedford | 14,408 |
| 2141 | Cambridge | 14,402 |
| 1778 | Wayland | 14,070 |
| 2458 | Newton | 12,706 |
| 1879 | Tyngsboro | 12,385 |
| 2465 | West Newton | 11,823 |
| 2493 | Weston | 11,759 |
| 1463 | Pepperell | 11,667 |
| 1450 | Groton | 11,212 |
| 1862 | North Billerica | 11,126 |
| 1754 | Maynard | 10,671 |
| 1460 | Littleton | 10,084 |
| 2460 | Newtonville | 9,888 |
| 1863 | North Chelmsford | 9,570 |
| 2466 | Auburndale | 8,859 |
| 1432 | Ayer | 8,118 |
| 1469 | Townsend | 7,168 |
| 1775 | Stow | 7,111 |
| 1464 | Shirley | 7,092 |
| 2461 | Newton Highlands | 7,049 |
| 2468 | Waban | 5,589 |
| 1719 | Boxborough | 5,462 |
| 1773 | Lincoln | 5,216 |
| 1741 | Carlisle | 5,209 |
| 2142 | Cambridge | 4,474 |
| 1770 | Sherborn | 4,404 |
| 2464 | Newton Upper Falls | 3,440 |
| 1827 | Dunstable | 3,359 |
| 1431 | Ashby | 3,187 |
| 1474 | West Townsend | 1,902 |
| 1731 | Hanscom Afb | 1,784 |
| 2462 | Newton Lower Falls | 1,438 |
| 1718 | Acton | 737 |
The data shown reflect ZCTAs from the US Census. As of 2024, there are 81 ZCTAs in Middlesex County, Massachusetts (US Census).