Jasper is the oldest settlement in the area often described as the Platoro mining district. The area was initially prospected in 1879 or earlier (accounts vary) by miners from Cornwall, England. The two adjacent camps of Cornwall and Jasper were established at the base of Cornwall Mountain.
Cornwall was initially the primary camp and reportedly had a post office from 1879 to 1882. By 1882 the two camps were consolidated as the town of Jasper and the Jasper post office was opened.
Some sources have stated that a post office was not established at Jasper until the 1890s. This appears to be untrue based on available information, however it should be noted that many of the details of Jasper's early history are unclear.
The Jasper post office appears to have closed and reopened at least once (years unknown) but closed for the final time in 1927.
In the 1980s the land that was the original Jasper town site and surrounding area was purchased by developers. The area now consists over over 200 rural properties that are primarily seasonal mountain cabins.
The 1917 publication Geology and Ore Deposits of the Platoro-Summitville Mining District, Colorado by the Colorado Geological Survey includes a bit of history on Jasper (the rest of the text on this page is quoted from the book).
Jasper is located in the Alamosa valley, just below where the river makes a great sweep around the northern base of Cornwall Mountain. Next to Summitville it is the oldest of the towns to be located in the district under consideration. It was founded in 1874-1875, at which time the first ore prospects were opened up.
The Perry mine was the first to be located and was discovered by Andrew Johnson, with whom Alva Adams was in partnership. Later associated with these men were G. G. Calkins and Pascal Craig. These men, together with Frank Moody, who later became interested in Jasper and laid out the townsite, still own most of the territory around Jasper. They control the Perry and Gaudaloupe mines under the name of the Cornwall Mining Company.
The Miser mine; the only other mine of consequence at Jasper is owned by Frank Moody, Dr. Ross, G. W. Ballentine and John Gabriel, all of Denver.
About two and a half miles above Jasper in the Alamosa valley is a group of old buildings and workings called the Sanger mine. Interesting tales are told as to the manipulation of this property, tales that are perhaps not possible to verify, but that are commonly accepted as true.
The story goes that the founders of this enterprise claimed to have a mountain of what they termed "bird's-eye porphyry" that had an average value of ten dollars a ton. After securing all the money possible by means of these alluring but false representations, the too confiding investors were swindled out of their money and the "mine" ceased operations. There is no doubt about a mountain of rock, but it assays only a small fraction of what was claimed.
However much truth there may be in this story, it remains true that the unsavory reputation gained thereby for Jasper has operated to discourage investment in such genuine mining enterprises as Jasper may have to offer.