The Philadelphia Print Shop West always has an good inventory of original, antique maps of Colorado, which range from maps before 1861–showing the area where Colorado was created–up to the early twentieth century. You can see our current inventory by clicking on the link below.
Colorado was created as a territory in 1861, with land taken from the territories Kansas, Nebraska, Utah and New Mexico. This was done in order to give the large population who descended on Denver and other towns in the foothills of the Rocky Mountains their own, local government. Previously most of those settlements were within the jurisdiction of the territory of Kansas, with its capital about 550 miles to the east. The territory was created as essentially a rectangle, 4 degrees in height and 7 degrees in width. Fifteen years later, in 1876, Colorado was admitted to the Union, thus it is often called the “Centennial State.”
The eastern part of Colorado, east of the continental divide, was originally part of the Louisiana Territory, with most of that part being the western half of the territory of Kansas from 1854 to 1861. The western part of the state was originally part of New Spain and then Mexico, part of the Mexican states of Upper California and Texas. The Republic of Texas and then the state claimed a “chimney” of land just west of the continental divide as far up as Colorado, but it gave up this claim for its present border in 1850.
As it was hard to map the mountains (not done in any systematic manner until the Hayden surveys beginning in 1873), there is a clear progression of mapping the Rockies over time. [Click here for reference book on the counties of Colorado] Colorado also expanded its counties from the original 17 counties and one Indian reservation in 1861 to its 64 counties in 2001; the history of this can be useful in dating maps.