Two Staffordshire council areas are predicted to have some of the highest proportions of over 50s by 2029, according to a BBC-commissioned study.
Staffordshire Moorlands was predicted to have 50.4% of people aged 50 or over, with South Staffordshire having 50.1%.
The UK average was for 41.2% of the population to be that age by then.
The research carried out by Experian looked at how areas would be affected by an increasing ageing population.
It showed the South Staffordshire Council area had the highest rate of pensioners providing unpaid care in England.
According to 2001 census figures outlined in the study, 13.6% of pensioners there had undertaken such care.
Unpaid care refers to looking after or supporting family members, friends, neighbours or others because of long-term physical or mental health problems, disabilities or problems related to old age.
Nick Maslen, Age UK South Staffordshire chief executive, described the South Staffordshire authority area as rural.
He said: "It is more likely people could be moving out to get jobs in surrounding urban areas so could be less likely to be available to support older relatives.
"From an organisational point of view at Age UK we want to ensure older relatives are adequately supported and getting the help and resources they need to support their loved ones.
"This could include giving these carers sufficient 'me' time to recharge their batteries, such as respite care - for example, when somebody else comes in for a night or day-sitting service to sit with the person being cared for, while the carer goes out."