(Image source: Library of Congress Map Collections)
The above map, created by George Washington in 1766, depicts
“A plan of my farm on Little Huntg. Creek & Potomk.” This map, which is publicly viewable at the Library of Congress Map
Collections and downloadable as a high-resolution JPEG2000 file, is included
in the Collections’ “Cultural Landscapes” section, which highlights the ongoing
cultural construction of United States and World landscapes through the ways individuals, communities, and nations modify land. This subsection of the online
Collection places an array of cartographic materials into conversation: a set
of local maps authored by George Washington, a series of maps of Liberia
created by the American Colonization Society, and a store of historical U.S.
atlases.
One of the distinguishing features of The Library of
Congress’s Map Collection is that it is part database, part exhibit. The online Collection boasts
sophisticated cataloguing and imaging standards, allowing users to zoom in on
maps, examine details, download high-resolution image files, and refer to
helpful notes about the map’s physical features and provenance, including
scale, media, size, accompanying materials, and source. The site also offers helpful advice
about copyright, noting that materials in the collection are generally not
copyrighted materials; the maps “were either published prior to 1922, produced
by the United States government, or both.” The site clearly aims to make the Library’s
cartographic collections freely available and digitally accessible and to
encourage users to download and use these materials for study, education,
research, and enjoyment. The site
intersects at many points with the Library’s larger “American Memory” project,
which has digitized over five million items from the Library’s Collections since
1996.
I am interested in the possibilities of a maps database such
as the Library of Congress Map Collections partly because of the prospect of
using historical maps within Google Earth, and partly because our Visual
Rhetoric workgroup is preparing to host an upcoming workshop, “Best Practices
for Digital Images”
on Friday March 26th at 1 pm.
One component of the workshop will be an introduction to the many rich
image databases that are available on the web. To that end, some of our posts over the next few weeks will
serve to review and evaluate some of these databases.
Three significant, online map
databases are The Library of Congress Map Collections,
the Perry-Castanada Map Collection
at the University of Texas Libraries, and the David Rumsey Map Collection.
These collections all have large holdings that are available
to the public and offer downloadable images, though only the Library of
Congress and the David Rumsey Collection offer consistently high-resolution
downloads. (The Perry-Castanada
Map Collection seems to prioritize keeping files to a manageable size for its users; the website claims that most of its images, usually JPEGS or PDFs, are kept to size standards of 200K to 300K.) These three collections, run by a
federal organization, a public university, and a private company, respectively,
vary widely in terms of cataloguing and indexing practices, image quality, image
context, and general online experience.
My aim today will be to offer a very brief overview of the
first two image collections, Library of Congress Map Collections and the
Perry-Castanada Map Collection. (I'll discuss the Rumsey Collection in a later post.) I
will give an expanded analysis of the features and utility of Library of
Congress’s Collection for pedagogical applications.
The Library of Congress Map Collections, the online arm of
the Library of Congress’s Geography and Map Division, represents a small
fraction of the holdings of the Map Division’s collection, which includes more
than 4.5 million items. The
Library of Congress Map Collections began as a massive digitizing project in
1995. The Library does not estimate how many maps are online, but
notes that new materials are digitized and added continually.
The Perry-Castanada Map Collection includes more than
250,000 maps, 11,000 of which are available for online viewing. (In addition, maps from the
Perry-Castanada Map Collection can also be physically checked out by students,
faculty, or the general public for a two-week borrowing period.) As I noted above, the Perry-Castanada
Collection does not prioritize providing high-resolution images or downloads of
their materials; their files, generally formatted as JPEGs, GIFs, or PDFs,
are considerably smaller than those of the other two sites. The Perry-Castanada Collection does
offer categorized links to hundreds of other map collections though, including
the Library of Congress and The Rumsey Collection, as well as other research
collections and independent web sites.
While each digitized map is indexed in the Library’s general catalogue, the
Maps Collection does not include the catalogue information or a link to the catalogue entries, so, in fact,
the amount of information about the map available with the image is minimal, usually including the title
of the map or atlas in which it was printed, its publication date, and sometimes the organization that
published or produced it. The
user has to separately look up the map in the online catalogue to
obtain full information. The full catalogue entries offer additional information such as the map’s
author, but the general purpose catalogue does not give the depth of information
one might expect from a special collections catalogue entry, including detailed notes about medium, size,
inscriptions, accompany materials, or provenance.
As I noted earlier, the Library of Congress Map Collection
works like a database and an online exhibit at once. The materials are indexed via a number of different methods: the
whole collections is divided into seven major thematic categories, which allow
users topical entry into the cartographic resources. Those categories include
- “Cities and Towns” (which includes a number of
panoramic maps, a cartographic style popular in the late nineteenth and early twentieth centuries)
- “Conservation and Environment” (including the
subcollection, “Mapping the National Parks”)
- “Discovery and Exploration”
- “Cultural Landscapes”
- “Military Battles and Campaigns” (including
American Revolution and Civil War maps)
- “Transportation and Communication” (including a
collection of Railroad Maps)
- “General Maps”
Nearly every collection includes a “Special Presentation,”
an online exhibition with text and images that invites users to delve into some
selected resources within the collection, rather than using the site
by entering specific search terms.
This feature allows users to have a curated, museum experience, clearly
serving not only the Library’s goal of making documents available to the
public, but also its educational goals.
While users can browse within these thematic categories, which
include their own Collection Guides, users can also search by keyword, or
browse indexes by geographic location, subject, map creator, or map title.
Indeed, as the above list of browse-able indexes suggests,
the site relies heavily on browsing to make its resources available to users.
For example, as the visitor enters the Railroad Maps Collection,
she finds only a very cursory introduction to the collection—a total of five
lines of text—on its home page, and this Collection happens to include no
curated “Special Presentation” to introduce the user to the Collection’s
material, so searching or browsing become her best methods of accessing
information. Fortunately, the
Geographic Location Index offers a robust, visual, clickable map icons to help users locate materials by
country (Canada, United States, Mexico, and West Indies), U.S. region, and U.S.
state.
In this way, the Library of Congress Map Collections site
combines sophisticated cataloguing methods with an inviting, browse-able online
environment. The icons that
accompany the seven thematic categories perhaps best express this mission of the site: each is a
collage of multiple materials from the category, with numbers identifying the source of each element of the collage, which are clickable:
(Image source: Library of Congress Map Collections)
The Cultural Landscapes icon, for example, pairs a detail
from the 1766 Washington map (pictured in full at top) with a detail from an 1867 American
Colonization Society map, “St. Pauls River, Liberia at its mouth.” The clickable collage, which links to
each element's catalogue page, represents the site’s values: user-based discovery (facilitated by either browsing or searching), curated experience, thematic intersections, accessibility, and high-quality image and cataloguing standards. By clicking on the category icon, the user not only enters the "Cultural Landscapes" section, but is confronted by provocatively juxtaposed visuals accompanied by links to each detailed source page.
Not surprisingly, the site offers extensive materials for
teachers, including classroom ideas, lesson plans, and primary source sets
(groups of images related to a historical period or theme) through its
“Collection Connections” section.
The Collection’s choice of somewhat unusual file formats for
images is, perhaps, an unfortunate extension of the value placed, at once, on
accessibility and high quality that I appreciate throughout most of the site. Rather than offering more common image
file formats such as TIFFs GIFS, or JPEGS, the Library has chosen to compress
their large documents as JPEG2000 and MrSID files to preserve detail and enable
high-resolution downloads. Both of
these formats require plug-ins, and while the site offers links to free
versions, I would have liked to have available a low-resolution option (a GIF
or JPEG) that required no software plug-in.
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