Historical Maps Online

by David Rumsey

Editor's note: David Rumsey writes about his collection of more than 150,000 historical maps of the Americas and the world, many of which he has made available free to the public in an online map library. At O'Reilly's upcoming Where 2.0 Conference David will draw on his personal map collection, as well as his work with geographic information systems, to discuss how information of all kinds has been mapped and will be mapped in the future.

Over the past 20 years, with the help of dealers, bookstores, auction houses, and other collectors, I have collected more than 150,000 maps of eighteenth- and nineteenth-century North and South America. Scores of scholars, researchers, and others interested in history and the humanities have viewed the physical collection housed in San Francisco, California. The collection also features world maps, and includes atlases, globes, school geographies, maritime charts, and a variety of pocket, wall, children's, and manuscript maps. Driven by an intense desire to make the collection available to the public in an intimate setting, in March 2000, I launched, a website that allows free viewing of my maps via high-resolution images on the internet.

The website now has over 10,000 historical maps available for close examination. The sophisticated, yet simplified software allows visitors to view maps side by side, zoom in for inspection of the smallest details, as well as save and print. A comprehensive catalog provides information about each map's cartographic relevance and provenance, author, publisher, and date of publication, and other historical and geographic facts. Users can launch a simplified browser-based viewer or download and install a feature-rich Java client.

The website also has a browser-based geographic information system (GIS) viewer. The interactive web GIS allows geographers, cartographers, and researchers to integrate historical maps with modern satellite imagery, aerial photos, and other geospatial imagery.

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Figure 1. Home page of the David Rumsey Map Collection

When I began collecting maps in the early 1980's, eighteenth- and nineteenth-century American mapping was not a popular subject with most map collectors. Thus, I was able to assemble an expansive array of maps very quickly. As it happened, the cartographic publishing business in the United States was forming during the eighteenth and nineteenth centuries. American mapmaking businesses often were interconnected, such as those of Colton and Johnson, Melish and Tanner, and Finley and Mitchell. These relationships are important when trying to recreate a comprehensive cartographic history of the time.

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Figure 2. Group window of the online collection, including thumbnails, data, and searching features

Because I wanted to record these relationships and other information about the maps as I collected them, I used a catalog database. The database not only preserved important information about the collection, but also allowed me to shape the growth of the collection with truly contextual collecting--seeing the relationships between the collected maps by subject, graphic type, time period, author or publisher, or geographic location. The use of a catalog database allowed me to see the collection in a data space and this allowed the shaping of the collection into a coherent whole. It also laid the groundwork for building the online collection, although I did not realize that until much later, when the internet came into existence.

Beyond atlases, the collection consists of individual maps, globes, puzzles, books with important maps (such as Lewis and Clark's published accounts), charts, and cartography in ephemera and unusual forms. Maps by their nature connote many forms of expression: William Henry Holmes's 1882 topographic drawing of the Grand Canyon is as much art as it is a map, and Samual McCleary and William Pierce's 1850 wood puzzle titled, Geographical Analysis of the State of New York, is the earliest known map and children's puzzle in the United States. It was a tool for teaching geography. Maps were also used in historical accounts: a large number of exploration books, government documents, and reports are part of the collection. They detail the official exploration and surveys used to map the United States as it expanded westward.

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Figure 3. The Image Workspace window, where maps can be enlarged and compared

One of the special gems in the map library is John Melish's Map of the United States published in 1816. This was the first large map to show the United States from coast to coast, and is considered a precursor of the later popular notion of Manifest Destiny. Melish was also a cartographic poet who, on the map, described the Texas panhandle as "Immense Plains of light salt sand mixed with fragments of Snail shells, moved with the wind, discovering Peaks of Volcanic Rock."

Where 2.0 Conference.

To make the collection available to a larger audience, I first considered publishing a print catalog, using the collection database as the source. However, this option would not allow people to truly study the original maps. With my growing interest in software and the internet, around 1997 I decided to create a software program that would display my collection via the internet, through collaboration with Luna Imaging. Placing the collection online and adding internet GIS capability was no small feat. The site required years of time-consuming and careful scanning, experiments with several display and web technologies, and GIS integration.

During this time, I began the arduous process of converting historical materials to high-quality digital images, and converting my existing database catalog to an online catalog of my map library. My database catalog contains a detailed compendium of cartographic materials and notes to connect the items. This record was quite useful in developing the online cataloguing system during the scanning process. Complete atlases were scanned, as were covers for pocket maps, puzzles, and their cases. Folding globes were shown compressed and then opened, and maps were shown enclosed within books. Each subset or group within the collection has a unique number to tie all of its components together. Individual items in the group have derivations of the unique number, and by numbering each record sequentially, the items appear together and in the correct order. Thus, if one searches for an entire atlas, all of the pages will come up together and in the proper order. In addition, when browsing, the cover for a map will appear next to the map itself. I was also able to create digital composite images of maps that were intended to be joined by the cartographer and engraver but were separated in the bound books. An example is Henry Popples's 1733 Atlas of the British Empire in America.

On March 15, 2000, the map library site was launched on the internet with more than twenty-three hundred maps. The number of visitors to the site in the first few months was astonishing: we averaged over ten thousand visitors a day. Feedback from users was immediate and revealed that a number of K-12 teaching resource groups, Civil War buffs, university map libraries and history departments, home schoolers, and the general public were keenly interested in this type of online library. Since the launch date over two million people have visited the site and used its resources.

By 2001, I was working with Telemorphic, Inc., a GIS software developer, to modify their web browser for general image analysis and visualization. We specifically tailored the software to allow people to see four different maps at the same time. The Quad View feature enables people to view a historical map next to other historical maps as well as contemporary satellite imagery or modern raster and vector data of the same area.

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Figure 4. David Rumsey preparing a map for scanning

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