Iowa Historical Imagery and other spatial data served in ArcGIS Online
Some key spatial data from longstanding data portals are making their way onto platforms such as ArcGIS Online. One of these is the data from the Iowa Geographic Map Server, served from the Iowa State University GIS facility. The data set, searchable on ArcGIS Online via the keywords “Iowa Geographic“, is one of the finest examples of the holdings of a state data depository in an easy-to-use format.
The data available includes aerial photographs from the 1930s, 1950s, and then every decade from the 1970s onwards. Also included are an atlas from 1875, a general land office survey from the 1800s, a hillshade from Lidar data, the public land survey system, civil townships, and watershed boundaries. Changes in agricultural practice, urban forms and size, river meanders, and much more can be explored via this map. In addition, one can add the individual layers to one’s own map by pointing to the server URL found in the metadata for each layer. That the metadata are well populated is another reason that the data portal has long been one of my favorites. If one needs to download the data, those data sets are still available via the data portal at Iowa State University on http://ortho.gis.iastate.edu/. While even more data are available via the data portal itself at Iowa State University, it is wonderful to be able to quickly browse a subset of the data via the ArcGIS Online map. ArcGIS Online contains tools such as making layers transparent, adding map notes and bookmarks, and the ability to use the Iowa portal layers as a backdrop for one’s own data. In addition, as a teaching and research tool, the way the data are served in ArcGIS Online allows land use changes to be quickly observed and measured without having to download each layer and loading them into desktop GIS software.
As data from portals such as the Iowa Geographic Map Server migrate to platforms such as ArcGIS Online, the data user will have additional ways to access that data. It takes a commitment from data providers to serve their holdings onto these platforms, but data users in government, nonprofit, industry, and academia will all benefit. Learn more about data portals, data platforms such as ArcGIS Online, and data types in our book The GIS Guide to Public Domain Data, and keep an eye on this blog.