The rally was first held in 1965, and conceived as a fundraiser for the upkeep of Masham Town Hall, which had been donated by the Lister family of nearby Swinton Park in 1913 but which had fallen into disrepair.
Organisers took advice from a similar steam traction fair at Pickering, and after moving to a site at Low Burton, attracted attendances as high as 22,000 people.
Several generations of the same families who showed their vehicles at the first rally have taken part in the event since and still turn out today.
Yorkshire Post photographer Tony Johnson went along.
9. Next generation
Six-year-old Alfie Ward with his 1916 Sentinel steam wagon Photo: Tony Johnson
12. Steam lorry
Richard Frank from Stokesley with his 4½” inch scale Foden steam lorry at Masham Steam Rally Photo: Tony Johnson