Nearly half of all bus routes in England receive subsidies from councils and are under threat, the Local Government Association has warned.
It said councils had struggled to maintain the subsidies in the face of a funding gap expected to exceed £5bn by 2020, leaving vulnerable residents isolated and unsupported.
Buses outside London are run commercially by operators with councils able to subsidise other routes judged socially necessary.
The LGA said that since 2013-14 there had been 297 million fewer journeys made, equivalent to a 6.4% decrease.
It cited government figures that showed 15,634 routes ran without council subsidy, 56% of the total, while 8,138 needed full subsidy and 3,987 a partial subsidy.
The LGA also called on the government to fully fund the concessionary fares scheme, under which councils spend £200m a year towards free off-peak travel for elderly and disabled people.
LGA transport spokesman Martin Tett (Con) said: “It’s nearly impossible for councils to keep subsidising free travel while having to find billions of pounds worth of savings and protect other vital services.
“Faced with significant funding pressures, many across the country are being forced into taking difficult decisions to scale back services and review subsidised routes.”