Maps many decades outdated are often still relevant, serving as a historical record and source document for tracking changing geographical data. With the emphasis on climate change and sea level rise, old maps are especially good at showing the shifting borders of wetlands, coastal areas, and changes in land use over time.
Most often the largest hurdle in making a historical map useful to a larger population is the scanning and warping, or georectification process. Scanning, while time consuming and requires great care, is but just the first step for accurately comparing old and new maps. A scanned map can be used for visual comparison, but georectification, the process of warping and digitally assigning coordinates to a scanned map, becomes important if a historical map is needed for any GIS analysis or use along side a Googlemap to accurately compare former and current conditions.
Check out the USGS Topoview Mapping Tool here and use them for your own projects!
