Britain's bus routes have lost 134 million miles of coverage over the past decade alone, according to the BBC Local News Partnership analysis.
It means the network has shrunk to levels last seen in 25 years ago.
The Campaign for Better Transport has warned that bus routes could be on course to suffer cuts to the same extent railways were closed in the 1960s.
Some cut-off communities have taken to starting their own services – although the government has encouraged councils and bus companies to work together to halt the decline.
The analysis shows the bus network in England has fallen to levels last seen in 1991 – even though passenger numbers are now 8% higher than they were then.
The East of England and South East were the only English regions outside London to see bus mileage increase over the past decade.
But North West England was the worst-hit region – losing some 23% of miles from its network in a decade.
Bus coverage in metropolitan areas has dropped by a tenth since 2013-14 alone – while rural areas saw bus routes cut by 7.8%.
Outside London, all English regions have seen bus subsidies reduced in the past four years, losing 32% of their subsidised miles on average.
Hardest hit areas
The top 10 hardest-hit areas were Bracknell Forest, central Bedfordshire, Shropshire, Surrey, Warrington, Gloucestershire, Wokingham, Stoke-on-Trent, Warwichshire and North Yorkshire.
Martin Tett, transport spokesman for Local Government Association, said: “It is hugely concerning to see such a decrease in bus journeys.
“Buses provide a vital service for our communities and a lifeline for our most vulnerable residents to go shopping, pick up medication, attend doctor appointments or socialise with friends.
“Councils know how important buses are for their residents and local economies and are desperate to protect them.
Mr Tett said it was “nearly impossible for councils to keep providing subsidised travel while having to find billions of pounds worth of savings and protect other vital services”.
He added: “Faced with significant funding pressures, many councils across the country are being forced into taking difficult decisions to scale back services and review subsidised routes.”
The Confederation of Passenger Transport, which represents bus operators said buses are the most used mode of public transport, with over 4.44 billion journeys undertaken each year.
A CPT spokesman said: “In the vast majority of cases, cuts to bus services have occurred where local authorities have withdrawn financial support to non-commercial routes.
“Returning to a regulated market would put further intolerable strain on those budgets.
“Recent research into the demand for bus journeys shows that most of challenges arise from external factors facing the industry. No single organisation can tackle all the issues.
“It is unfair to say that operators are risk-averse.
“Where routes become unviable, sound business decisions need to be taken and there are many examples of operators continuing to operate lightly used and uneconomic services.”
The full study is available here.
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