During the 1920s and 1930s, Montrealers and LaSalle residents swarmed to Rocky Beach, located near the Lachine Rapids, between 1st Avenue and 8th Avenue. On the pebbly sand were stands operated by the Bélanger, Dumas, Lussier and Leblond families, who sold soft drinks and ice cream there. During the 1930s, the street cars brought visitors to the foot of 4th Avenue. The beach was a victim of its own success and some residents wished they could keep their beach for themselves.
The popularity of the beach gave priest Joseph Allion of the Notre-Dame-du-Sacré-Cœur parish his best sermon topics—wearing a swimsuit on Sundays—as he considered swimsuits to be indecent, to say the least. Sometimes he went to the beach to see whether his parishioners were following his directions.
In July 1930, the City Council of Mayor Louis-Auguste Chatelle, and also a resident-owner of the Bronx district, voted in a bylaw to prohibit people from wearing swimsuits on the streets of LaSalle. In so doing, the municipal authority responded to the desire of priest Allion to maintain "good order and public decency".
In July 1943, the problem became worse: The City of LaSalle hired a police officer for the entire summer season in order to prevent the beach users from strolling through the streets half-dressed and thereby avoid "disgrace" in the district and, above all, preserve the City's reputation. It must be said that wearing a swimsuit was very poorly regarded, especially on Sundays. The men could not walk through the streets either without a shirt or sweater.