My answer is short with alot of links but I am sure it can be helpful as Sanborn fire maps are invaluable in recreating towns of the 1800's. They were detailed maps at a 50ft. to 1in. scale used for insurance purposes. They display lot numbers and, often times, building uses. They are available for a variety of towns and various dates in the late 1800's, not only in Colorado but nationwide. Here is a link to the ones at Denver Public Library, a library card is needed.

https://ezproxy.denverlibrary.org/login?qurl=http://sanborn.umi.com%2fcgi-bin%2fauth.cgi%3fcommand%3dIP_Auth

An example of a map portion pre "clear", Post clear, and portion of the key to the map to show type of info given:

https://imgur.com/gallery/lCJ2las

The lots marked with S's are shops, info on these can be found in city directories, an example for this particular maps year:

http://digital.denverlibrary.org/cdm/compoundobject/collection/p16079coll28/id/4320/rec/2

An example of Crested Butte Colorado:

https://imgur.com/gallery/4mheUni

and finally an example of how useful they can be:

Pinpointing the current location of the flashpoint of the Denver Anti-Chinese riots, October 31st, 1880. https://imgur.com/gallery/tBqtJKg

Also, that link to Denver digital library might yield results viewable in that form if you search town name and the word map from the home search.

Googling "Sanborn maps (anytown U.S.A.) should yield results for any one else curious about their areas.

Hope this helps. ✌😉

Here's some history from Castle Rock, Colorado, which fits your description. It was founded a little later than the period that you are looking for:

Castle Rock, first settled in the 1870s, is nestled in the heart of East Plum Creek Valley, surrounded by rocky buttes and featuring stunning views of the Rocky Mountain Front Range. Named for the prominent rock formation that overlooks the Town, the discovery of rhyolite stone in the butte near Plum Creek is what put Castle Rock on the map and made it an important station for north-south railroad traffic.   One of the original homesteaders, Jeremiah Gould, owned 160 acres to the south of “The Rock.”

At that time, the community consisted of just a few shacks for prospectors, quarry workers and other hired hands. In 1874, Gould donated 120 acres to “be known as Castle Rock.” Within a year, the new train depot brought the Denver & Rio Grande Railway to the community unloading supplies for ranchers, shipping rhyolite from the three local quarries, and cheese from the dairy farms in the surrounding area. The depot now houses the Castle Rock Historical Museum on Elbert Street, where visitors can relive the 125+ years since the Town’s inception.

http://www.crgov.com/2237/Town-History

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Some pictures:

http://visitcastlerock.org/about-castle-rock/history

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Now, to answer your question, it was greatly expanded due to mining. So, it was really just shacks for miners. There wasn't much in the way of "town."

At that time, the community consisted of just a few shacks for prospectors, quarry workers and other hired hands

Another plug for the Sanborn fire insurance maps, although they don't start to cover Colorado until after your period. But the Library of Congress has them available online — here are the earliest Colorado ones, which includes this 1883 map of Boulder, Colorado. The best part for your purposes is that businesses are labelled.

I will warn you that as one might expect the town changed rapidly from its founding in 1859 to 1883. Compare, for instance, this view of Pearl Street (the main street) from 1889 to this one from the 1860s. The local history collection has done bad things to their online usability lately, but they also have this set of views from the same era. This view of Boulder is supposedly from the same decade, but you can tell it’s later than the two sets above, with tree plantings and brick homes.