Recently I posted announcing the digitization of cartographic records from the Irrigation Division of the Bureau of Indian Affairs. While scanning those records, I came across some interesting maps that demonstrate the various stages a map went though before being published by the U.S. government.
Before the use of aerial photographs and the development of photogrammetry (the science of making measurements from photographs), maps began as a compilation of notes and sketches created by hand in the field using a variety of survey techniques and instrumentation. This compilation resulted in the creation of a manuscript map. Manuscript maps are maps that are hand-drawn or hand-painted. Below is a manuscript map (in two parts) of the San Carlos Irrigation Project located in the Gila River Indian Reservation in Pinal County, Arizona. Drawn in 1939, it is annotated in multiple color inks to denote features such as boundaries, roads, power lines, canals, etc.
Reproduction of maps centered around three separate processes: woodcut, copperplate engraving, and lithography. Each method presented pros and cons between image detail, cost of plate preparation, and quality of the finished product. Regardless of method, each process required the preparation of printing plates. The manuscript map shown above would have been used as a template to create a printing plate. Below is a printed copy of the above manuscript map.
For maps that required different color inks, separate overlays would be prepared for each color ink. The color overlays would be used in the creation of the color printing plates. Below are printed copies of the above map with hand-drawn color coded annotations. Each color used represented a different feature, as described in the legend on each map.
Once a printing plate of each color was created, the plates would be mounted on a press. Known as overprinting, each plate would subsequently be pressed onto a sheet of paper. Overprinting required exact precision. A few test copies (or proofs) would be made to work out any corrections that needed to be fixed. The below map is a first proof copy, printed on May 1, 1940, of the manuscript map featured at the beginning of this post. If you compare this printed map with the manuscript one, you will notice some differences in addition to the fact that the printed version is much smaller in size. One such difference is the color of some features; the electrical district boundary and all power and telephone lines are red rather than a mix of red, purple, yellow, and black. Another difference is the typeface and location of some print. Perhaps one of the most important differences is in the feature descriptions in the legend.
Once any corrections or adjustments have been made, a final copy would be printed. Finito!
Below is another copy of the same map. The color and typeface is not nearly as crisp as the proof copy.
Additional blog posts about unique maps and other cartographic records, may be found here. For more information on the Cartographic Branch, its records, obtaining copies, and conducting onsite research, please visit our website.
Sources:
- “Map Printing Technologies” webpage from The University of North Carolina at Chapel Hill. https://exhibits.lib.unc.edu/exhibits/show/comcarcre/mapprint.
- “Topographic Mapping” webpage from the U.S. Geological Survey. https://www.usgs.gov/educational-resources/topographic-mapping.
- The History of Cartography, Vol. 6, Cartography in the Twentieth Century. https://press.uchicago.edu/books/HOC/HOC_V6/Volume6.html.
- “Modern mapmaking techniques” entry from Britannica. https://www.britannica.com/science/map/Modern-mapmaking-techniques.
- “USGS Engravings Offered to the Public” article from the U.S. Geological Survey. Posted March 30, 2015. https://www.usgs.gov/news/featured-story/usgs-engravings-offered-public.
- “1. Intersections of Manuscript and Print” webpage from the Osher Map Library and Smith Center for Cartographic Education from the University of Southern Maine. http://oml01.doit.usm.maine.edu/1-ms-print.
- “Map Separates” report from the U.S. Geological Survey. USGS Fact Sheet 042-01. Published April 2001. https://pubs.usgs.gov/fs/2001/0042/report.pdf