Union Station was the largest and most opulent train station erected in Canada during the last phase in railway station construction. Construction began in 1913, but was delayed for several years because of World War I. The station was officially opened by the Prince of Wales on August 6, 1927. Construction on the station had in fact been completed eight years earlier. The Prince of Wales was issued the first ticket sold at Union Station, to Alberta for a cost of $71.20, which today would cost over $1,100. During this ceremony, the Prince of Wales was also presented with a gold key that unlocked the station.

On August 11, 1927, Union Station received and dispatched its first passenger trains.