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.
. Visitors look at the traction engines
Visitors look at the traction engines in the weather-damaged show field Photo: Tony Johnson
2. Visitors look at the traction engines
Visitors look at the traction engines in the weather-damaged show field Photo: Tony Johnson