Antique Colorado and Wyoming Map Circa 1880's-1890

Old map of Colorado with Wyoming on the reverse side circa 1880's-1890.
It is 11 1/2" x 14 1/2".
The maps indicate counties, cities, railroads, rivers,lakes, mountains and other topographical marks of that time period.
Light darkening of the paper and writing in pencil on the edge from prior owner stating the approx year the map was created.
No publisher information.