1946 Hotchkiss Wall Map of Denver, Colorado

This is a striking diazo or whiteprint c. 1946 wall map of Denver, Colorado, by the locally based Hotchkiss Map Company. Centered on Capitol Hill, this map covers all of Denver from Lakeside Lake to Aurora and from 54th Avenue to Englewood. An inset map of Englewood occupies the lower left while another inset on the lower right details the Denver Business District. The map is highly detailed showing streets, individual buildings, parks, route numbers, railway lines, churches, schools, and other features. It is extremely large - not to be confused with Hotchkiss' smaller but otherwise similar map appearing in his Denver guide. The diazo medium necessarily limits the number of maps produced - thus underscoring this map's exceptional nature.

Diazo Print or Whiteprint

The diazo print (whiteprint or diazo for short) is a photo reproductive technique best understood as a reverse cyanotype or blueprint. The process yields distinctive blue lines on white paper. Like cyanotypes, the diazo process gained popularity in architecture circles, where it was a simple and effective way to duplicate documents in the field. The earliest diazotypes appeared around 1880 and were adopted for military and field cartographic use from about 1895. The diazo process was commercialized in 1923, when the German firm, Kalle and Company, developed Ozalid, a patented diazo paper that made diazotyping even easier. By the 1950s, it supplemented cyanotypes as the reprographic technique of choice for technical drawings.

Publication History and Census

This map was issued by the Charles J. Hotchkiss map company. It was likely printed in diazo by Delbert W. Smith, the firm's resident whiteprint specialist. Although undated, the presence of the Lowry Aviation Field but lack of major highways suggests a date of about 1946-7. A smaller version of this map was printed in various Hotchkiss guides, but this wall map version is extremely scarce. We note no other examples on the OCLC but have knowledge of a few others in private hands.