Middlesex County Population 2018
Middlesex County's estimated population is 842,798 with a growth rate of 0.33% in the past year according to the most recent United States census data. Middlesex County is the 2nd largest county in New Jersey.
| Year | Population | Growth | Growth Rate |
| 2017 | 842,798 | 2,812 | 0.33% |
| 2016 | 839,986 | 1,654 | 0.20% |
| 2015 | 838,332 | 2,997 | 0.36% |
| 2014 | 835,335 | 5,344 | 0.64% |
| 2013 | 829,991 | 5,238 | 0.64% |
| 2012 | 824,753 | 7,164 | 0.88% |
| 2011 | 817,589 | 6,372 | 0.79% |
| 2010 | 811,217 | 139,437 | 20.76% |
| 1990 | 671,780 | 75,887 | 12.74% |
| 1980 | 595,893 | 12,080 | 2.07% |
| 1970 | 583,813 | 149,957 | 34.56% |
| 1960 | 433,856 | 168,984 | 63.80% |
| 1950 | 264,872 | 47,795 | 22.02% |
| 1940 | 217,077 | 4,869 | 2.29% |
| 1930 | 212,208 | 49,874 | 30.72% |
| 1920 | 162,334 | 47,908 | 41.87% |
| 1910 | 114,426 | 34,664 | 43.46% |
| 1900 | 79,762 | 18,008 | 29.16% |
| 1890 | 61,754 | 9,468 | 18.11% |
| 1880 | 52,286 | 7,257 | 16.12% |
| 1870 | 45,029 | 10,217 | 29.35% |
| 1860 | 34,812 | 6,177 | 21.57% |
| 1850 | 28,635 | 6,742 | 30.80% |
| 1840 | 21,893 | -1,264 | -5.46% |
| 1830 | 23,157 | 1,687 | 7.86% |
| 1820 | 21,470 | 1,089 | 5.34% |
| 1810 | 20,381 | 2,491 | 13.92% |
| 1800 | 17,890 | 1,934 | 12.12% |
| 1790 | 15,956 | 0.00% |