Mirror was named after the well-known English newspaper, The London Daily Mirror. When the Grand Trunk Pacific railway constructed a branch line between Edmonton and Calgary via Mirror, the railway decided that since Mirror was between the two centres it would become a divisional point. The railway crew proceeded to build a roadhouse, living quarters for train crews, a repair depot and an 8-billion gallon water reservoir. The company then surveyed the townsite and began advertising Mirror as the perfect place to live in newspapers throughout the United States, United Kingdom and Northern Europe. The railway company had great hopes that Mirror would become one of Alberta's largest cities.
Mirror was incorporated as a village on July 27, 1912. With the amalgamation of the Grand Trunk Pacific and the Canadian Northern Railways, the lines became the Canadian National Railway on October 4, 1922. Mirror was a railway town and the emphasis was on the large number of railway employees. Although, when the railway converted to diesel units it was not necessary for the railway to continue using Mirror as a divisional point. This left many of the railroad buildings such as the roundhouse, living quarters and the water reservoir available to industries. The phasing out of Mirror as a divisional point was gradual. Railway crew members were transferred to other areas or they decided to retire. As a result, the population of the area significantly decreased yet many retired farmers and railroad workers took up residence.