Hi Gary! Thanks for your comment!
I would strongly recommend checking out the Denver City Directories (available online: goo.gl/1zLCvT).
Denver City Directories date from 1873 and are arranged by name of resident or business name. Towards the back of each volume is a business directory of sorts. For example, I found the "restaurant" heading in the back of the 1882 City Directory (page 663) which lists nearly a full page of Denver restaurants operating at the time: http://goo.gl/E5BB7Z
Thanks for reading, Gary!
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