Wednesday, October 20, 2010

Local History Mapped has just been launched on Calisphere!

Click to see larger Images

Local History Mapped consists of five maps of California with approximately 350 images from Calisphere plotted on the locations they depict. Users can browse the maps to find images, explore their neighborhoods, and learn about local history. Each map is on a different theme—civic buildings, disasters, transportation, city scenes, and everyday life—and includes a short essay with selected images and a “teachers’ toolbox” with ideas and activities for K-12 educators.  The California Historical Society has contributed to this project with several period photographs.  The maps will be accessible from the Calisphere homepage.

From Calisphere:

Local History Mapped: How We Mapped the Images

As we selected images for this feature, we tried to ensure representation of a variety of regions and communities. Even if their precise locations could not be determined, we decided that some images were worth including because they are visually rich and document what was happening in a defined area at a specific time in history. For all of the images in this collection, we have identified and mapped their locations to at least the city level.

Finding the Geo-coordinates

Pinpointing the geo-coordinates of each image in Calisphere’s Local History Mapped took some historical detective work. We followed five steps to find the address or cross-streets for each image:

1. We mapped the image to any location information contained in its description. For instance, the titles of some photographs contain the addresses of buildings pictured.

2. If there was not enough information in the description, then we looked for any landmarks and features in the image that could help identify its location.

3. We compared whatever information we could find there with information on trusted websites, like those of local historical societies.

4. We also searched the Internet for contextual information that would help define the location (for instance, looking up a modern-day stretch of historical Route 66).

5. Finally, in some cases, we submitted a reference request to the institution that contributed the image. Staff at these repositories applied their knowledge of local and regional history to help us map the images.

If you have additional information about an image that will help us more accurately map it, please let us know at

What “Location on map is approximate” Means

When you see the statement “Location on map is approximate,” it means that we were not able to identify its exact geo-coordinates (address or cross-streets). We plotted these images to the most specific known level of detail, such as “the waterfront” or “the north side of town.” There are several reasons why we might not have been able to find the exact address for every image:

1. Something changed: Sometimes, the physical environment had been altered since the photograph was taken. For example, we could not map some structures destroyed in the 1906 earthquake because the street patterns of some of the affected towns were changed in their rebuilding. And as a result of California’s rapid population growth in the mid- to late 20th century, areas of farmland were transformed to strip malls and housing developments. Urbanization also brought re-zoning and new ways of organizing and naming the landscape.

2. Not enough information: Other times, we found photographic evidence of people and places but did not have the metadata (location, date, and other information about the image) necessary to support exact mapping. Some family photographs that help us understand the diverse individuals living in California throughout its history did not include specific enough information about where the photograph was taken.

3. No information: Finally, and perhaps most frequently, we do not know much about an image because its creator or collector did not record its details. Libraries, archives, and museums work hard to identify all the facts about the articles they collect, but sometimes these details are simply lost to history.

All of the maps are available from the Calisphere homepage; you’ll notice a new space highlighting this in the “Collections for Educators” section. Or, if you’re feeling adventurous, you can view a map at random with the URL:
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