Access to free cash machines is declining in some of Bristol's poorest communities, according to experts from the University of Bristol.
Researchers say this could have a negative impact on people who don't use online banking or have issues with mobility.
They're warning a lack of access to ATMs could cause "cash deserts", hitting Bristol's deprived areas the hardest.
Research carried out by the university found "stark differences" in access to free cash machines in different areas of the city.
Free cashpoints and bank branches were concentrated in areas of economic activity, including Clifton.
ATMs owned by firms that increasingly charge people to take money out are found in more deprived communities, according to the study.
On Whiteladies Road - also known as the Golden Mile - 29% of cash machines were not owned by banks, compared to 89% in the more deprived area of Stapleton Road in Easton.
The study found two-thirds of cash machines that started charging between October 2018 and March 2019 were within the city's poorer communities.
As part of our research, we regularly encountered people who found it difficult to access mainstream banking products. They do not use digital payments because they find it easier to manage their money in cash, and simply had a lack of trust in digital banking. For these people, cash very much continues to be king.
The researchers said current discussion is focusing too much on the overall number of cash machines and bank branches in the UK, without understanding where they are.
Dr Tischer said: "While a future without cash may be almost inevitable, if the patterns found in Bristol are replicated nationally, it's likely we'll see a return to old geographies of financial exclusion, with deprived communities struggling most".
According to the research, almost half of fee-charging cashpoints in the city have no free alternative within 250 metres.
This could have a negative impact on those with mobility issues, they're warning.
Jamie Evans, from the University of Bristol's Personal Finance Research Centre, said:
Despite the rise in digital payments, cash remains key to day-to-day economic activity - especially for many marginalised and vulnerable people in our society. Communities need to be able to access cash, but the market is not currently functioning in their best interests. Ironically, those who are best served appear to be those who are most likely to use digital payments.
Mr Evans continued: "The provision of cash infrastructure appears not to reflect the geographical need for it by some of the older and less well-off residents. Future policy should seek to understand the needs of such groups and take these more fully into account."
Sara Davies, who co-authored the report from the university, said more than three quarters of convenience store customers pay by cash.
She also said it's "fundamental" to businesses such as taxi drivers or window cleaners that cash remains easily accessible.