The Estevan riot, also known as the Black Tuesday Riot, was a confrontation between the Royal Canadian Mounted Police and striking coal miners from nearby Bienfait, Saskatchewan which took place in Estevan, Saskatchewan on September 29, 1931. The miners had been on strike since September 7, 1931 hoping to improve their wages and working conditions. They had been organized by the Communist Party of Canada's trade union umbrella, the Workers Unity League. Several hundred assembled in Estevan with their families to parade through the city in order to draw attention to their strike. The RCMP confronted them and attempted to block and break up the procession. Police violence broke out and the police opened fire on the strikers, killing three of them. Many strikers were wounded and arrested.
It remains a controversial event to this day in Estevan. The three striking miners who were killed have the inscription "murdered by RCMP" on their headstone, and locals have alternately erased and restored these words up to the present day. The Saskatchewan Federation of Labour has created a plaque memorializing the strikers.