The lands where the Town of Río Mayo is located today were first explored by Lieutenant Colonel Jorge Fontana, who approached this place in 1885 and discovered the river the Tehuelche natives used to refer to as A’Ayones (which stands for “bog land”) during an expedition encouraged by the Government of Chubut, whose governor was Fontana himself.
During this expedition (one of whose merits was also having explored the area known as Trevelin today), Mr. Gregorio Mayo stood out. He belonged to “Chubut's Riflemen” and, being one of the governor's assistants, he promoted the creation of reports on the most favorable areas for crops and sheep-husbandry. It was the riflemen who did some reconnaissance in the area and investigated the Senguer River from the lake to its mouth in Lake Muster.
Later on, some travelers journals were found which revealed that the route they had taken was east-southeast and that they avoided the hill tops by going cross-country. They described the valleys as not big enough and of poor field quality. Thus, they determined their scarce utility for cattle raising. The accounts go on describing how they named “Franco” (Frank) a valley to the west and “Mayo” (May) the creek that went across it.
As a tribute to these men who explored the area and gave that name to the creek, Governor Fontana resolved to give the name of Río Mayo (May River) to that spot. The town itself was created in 1935 and in 1941 it had its first Neighborhood Development Committee, authorized by the Government of Chubut.
Río Mayo was considered an ideal site for rest and cart drivers crossings, as well as for those who dared to endure its harsh weather conditions and settle down in this area, which gradually began to become more and more populated. Sheep-husbandry was and still is the most outstanding economic activity in the area.
As a result of its natural resources and the fact that it lies within the Central Patagonian region, Río Mayo was declared Rural Tourist District in 2001. Besides, ever since 1984 it has had its own festival organized by its denizens: Sheep-shearing National Festival, which has become more and more important as time went by.