Use of the name Ajax for Aspen Mountain became common in the latter half of the 2oth century, after the development of Aspen into a skiing resort started.
Geologic maps from Aspen’s period as a silver-mining town in the late 1800s denote the point on Aspen Mountain where the original octagonal 1946 Sundeck later stood, as Ajax Hill. The name is likely derived from the Ajax mine nearby.
When the first chairlift was constructed in 1946, it carried riders up Aspen Mountain to a point near Midway, from where a second lift carried passengers to the top of Ajax Hill.
Over the years that followed, people would refer to Aspen Mountain as Ajax Mountain and the names were used interchangeably. In 2000, the Aspen Skiing Company tried to formally change Aspen Mountain’s name to Ajax to avoid marketing confusion with the other three Aspen ski mountains, but the idea was abandoned after meeting with local opposition.