At the beginning of 1947 the first elections in fourteen years were held for state governors. Adhemar de Barros, elected in São Paulo with large support from the communists, was an old ally of Vargas who ran his own political party, the Progressive Social Party (psp), and began to compete with Vargas himself for the working-class vote. His campaign for the Government of the State of São Paulo had been based on lowering the high cost of living. He promised strict price controls on basic necessities and an intensive campaign against price rises. Therefore, when the Mayor of São Paulo announced a rise in transport fares a few months after the election of Adhemar, the hostile reaction spread through the city like wildfire. Rapid growth and the disregard of public authorities contributed to a chaotic and profoundly unequal urban landscape, where the most visible problem was the public transport system. The aim of this article is to understand the popular reaction to the rise in bus and tram fares which led to the largest urban riots in the history of the city, at that time already the largest industrial metropolis in Latin America.