There are around 10,000 miles of historic paths missing from the map in England and Wales, according to a walking charity.
The Ramblers said these paths, some of which have become overgrown and unusable, did not make it onto the official maps that councils drew up in the 1950s.
It warns that unless these missing paths are claimed by 2026 - the cutoff date for adding paths to maps based on historic evidence - they could be lost forever.
It is calling on the public to help identify these missing rights of way and add them to the charity’s mapping website.
Jack Cornish, Ramblers Don’t Lose Your Way programme manager, said: ‘Our paths are one of our most precious assets. They connect us to our landscapes – ensuring we can explore our towns and cities on foot and enjoy walking in the countryside – and to our history and the people who formed them over the centuries.
‘If we lose our paths, a little bit of our past goes with them. This is our only opportunity to save thousands of miles of rights of way and time is running out.’
The Ramblers is also calling on the Government to extend the deadline for registering historic paths by at least five years.