Falling birth rates and medical advances have left more US cities than ever with more elderly as young residents.
Experts predict within 40 years a quarter of the total population will be over 60 as the percentage of older people continues to rise.
A total of 18.5 per cent of the US population is currently over 60 - up from 16.3 per cent in 2000.
Northeastern cities dominate the top ten oldest populations, with Pittsburgh top with 23.6 per cent of residents aged over 60 but just 16 per cent under 15, according to research by demographer Wendell Cox.
Demographic expert Joel Kotkin said former industrial regions of the country have suffered most as people move to the south and west in search of work.
Eight of these areas, including Buffalo, Cleveland, St Louis and Detroit sit in the top ten.
Only established retirement areas Tampa - St Petersburg and Miami break their monopoly.