The latest population estimate by county shows that Franklin County’s population declined from 2000 to 2017 by about 670 people (or <1%), while the state and nation grew by 4.8% and 5.5% respectively. Of the fourteen counties of Massachusetts, Franklin County along with Berkshire County and Barnstable County (which is Cape Cod) declined in population.
| Geography | 2010 Census Population | Population Estimate 2017 | 2010-2017 Difference | 2010-2017 Change |
| Berkshire County | 131,219 | 126,313 | -4,906 | -3.7% |
| Barnstable County | 215,888 | 213,444 | -2,444 | -1.1% |
| Franklin County | 71,372 | 70,702 | -670 | -0.9% |
| Hampden County | 463,490 | 469,818 | 6,328 | 1.4% |
| Hampshire County | 158,080 | 161,834 | 3,754 | 2.4% |
| Bristol County | 548,285 | 561,483 | 13,198 | 2.4% |
| Worcester County | 798,552 | 826,116 | 27,564 | 3.5% |
| Plymouth County | 494,919 | 515,142 | 20,223 | 4.1% |
| Norfolk County | 670,850 | 700,322 | 29,472 | 4.4% |
| Dukes County | 16,535 | 17,325 | 790 | 4.8% |
| Essex County | 743,159 | 785,205 | 42,046 | 5.7% |
| Middlesex County | 1,503,085 | 1,602,947 | 99,862 | 6.6% |
| Nantucket County | 10,172 | 11,229 | 1,057 | 10.4% |
| Suffolk County | 722,023 | 797,939 | 75,916 | 10.5% |
| Massachusetts | 6,547,629 | 6,859,819 | 312,190 | 4.8% |
| United States | 308,745,538 | 325,719,178 | 16,973,640 | 5.5% |
