In 1909, the City of Montreal annexed De Lorimier and Saint-Louis of Mile End villages.
In that time period, Saint-Louis of Mile End was made up of various industries and contained the first tree-lined boulevard, namely today's Saint-Joseph boulevard.
In 1920, University of Montreal relocated to the mountain, while the francophone and anglophone communities moved to other new neighbourhoods. The economic bust of the 1930s prevented any real estate development in the area. In order to promote economic growth and control unemployment, the city engaged in large projects like the construction of Laurier clinic, the juvenile court (today it is the Canadian National School of Theatre), Sir-Wilfrid-Laurier park's chalet and the Iberville tunnel.
By 1962, St-Joseph's blvd. lost its greenspace and its trees.