A Leeds care home operator has been ranked as the nation's worst in a survey which also reveals that half of England's big providers have at least one in four failing homes on their books.
The figures emerged as county councils warned that an "unprecedented" boom in the elderly population across rural England was pushing local services to breaking point.
An investigation by consumer watchdog Which? has found that some parts of the country have more than half of their care home beds in homes rated as requiring improvement or inadequate.
The worst performer, Ideal Care Homes, which runs 16 homes across the Midlands, the North West and Yorkshire, had more than three in five classed as failing.
Which? analysis of Care Quality Commission (CQC) data shows that in six local authority areas, good quality care home places are so limited that 50% or more of local beds are in homes rated as requiring improvement or inadequate, making it less likely that people looking to move into a care home will be able to find a good place near where they live. That is an increase of nearly 70 per cent in just one year.
The County Councils Network, which represents all 37 county councils in England, said current funding practices did not take into account increases in the proportion of elderly residents - a figure that is now 11.7 per cent in North Yorkshire.
"Securing and retaining a stable staff group is key to delivery of a quality service in a care home and the council is aware that this is a challenge, not just in North Yorkshire, but across the country".
Ideal Care Homes said it was "deeply disappointed" with the ratings on its homes. He added: "Aiming for "good" and "outstanding" is our top priority and our frequent assessment of all our care homes demonstrates we are moving towards this".