When the Iowa Department of Transportation begins plans for a new roadway or expansion of a current one, they often review aerial photos to gain a historical perspective of the affected areas. Of course sorting through thousands of photos to find the one that depicts the right area is a very time-consuming task. So photomosaic indices were developed and now the University of Iowa Libraries have added them to the Iowa Digital Library.
Iowa Aerial Photo Indices Digital Collection (http://digital.lib.uiowa.edu/api) of over 2,000 aerial photomosaic index sheets, digitized by Historical Information Gatherers , represents a much larger collection of individual photos of Iowa counties in the University of Iowa Libraries Map Collection. Each “tile” in the mosaic corresponds to an individual photo, usual 10” x10”, that reveals much more detail about land usage.
These indices and the corresponding photos are often used by geologists and geographers, urban planners and geneologists, attorneys and civil engineers who are researching the previous uses of the land and planning future projects. On the photos themselves, researchers can discern historic building foundations; pre-mechanized farming methods; burial mounds (Office of the State Archaeologist has successfully used the photos for this purpose); old road beds; prior usage of lots for commercial purposes such as gas stations; and stream and river channels that have shifted from either natural or human causes.
The University of Iowa Libraries Map Collection holds over 150,000 aerial photographs of Iowa’s counties from the 1930s to the 1990s. Most of the photos are accompanied by photomosaic indexes that allow researchers to determine specific photos needed for projects.
Photomosaic indices, as well as individual Iowa aerial photographs, are available for public use in the Map Collection. To determine whether a particular photo is available for copying or scanning, please contact the Map Collection staff. Digital versions of some of Iowa’s aerial photos, including photos taken as recently as 2000, can be found on Iowa State University’s Iowa Geographic Map Server.
Though the quality of some of the pre-1955 indexes is poor, we still felt it was an important collection to bring into the Iowa Digital Library, because it gives researchers a place to start their search for more information. Some of pre-1955 paper indexes were obtained from the National Archives (NARA) and are photoreductions of the originals.
The Iowa Digital Library contains more than 175,000 digital objects—photographs, maps, sound recordings and documents—from libraries and archives at University of Iowa and their partnering institutions. The Iowa Digital Library also includes faculty research collections and bibliographic tools (holdings information for some library materials that are not otherwise accessible through the online catalog). Digital collections are coordinated by Digital Library Services, which manages the preservation, delivery, and structure of UI Libraries’ digital content.