According to data from the United States Census Bureau, the cities in New Jersey with the oldest populations are:

1. Haddonfield – 43.1%
2. Westfield – 39.5%
3. Summit – 38.7%
4. Ridgewood – 38.1%
5. Millburn – 37.8%
6. Glen Rock – 37.7%
7. Mountain Lakes – 36.9%
8. Wyckoff – 36.8%
9. Madison – 36.2%
10. Demarest – 36.0%

These numbers reflect the percentage of the population in each city that is 65 years of age or older. The rankings may be different if you were to consider other factors, such as the size of the population or the median age.