The United Church of Canada was founded on June 10, 1925 in Toronto, Ontario, when the Methodist Church of Canada, the Congregational Union of Canada, and 70 per cent of the Presbyterian Church in Canada entered into an organic union.  In Montreal, this meant joining of some churches and simply renaming others.  East End Methodist and Taylor Presbyterian became East End/Taylor United, Delorimier was renamed Zion United, Rosemount Methodist became Rosemount Central United, Rosemount Presbyterian was renamed Rosemount First United, and finally Trinity Methodist became Trinity United.

In 1932, East End/Taylor and Zion United combined to form St. Stephen's United who, in turn, joined Rosemount Central united in 1963 to form Mount Stephen United.  Then, in 1970, Mount Stephen United, Rosemount First United, and Trinity United amalgamated to form Trinity United Church as we know it today.