I'm working with a professor of American History who is interested in developing a mapping exercise for her students which will enable them to more deeply explore African-American life in Chicago in the first half of the 20th century.  This project (at the moment) will involve doing research in archives, newspapers, the census, and other sources, and attempting to map the dense web of African-American life in Chicago after the "Great Migration" and before WWII.

Currently we are looking at ESRI StoryMaps for this project, because a) this is a 100-level course, so the instructor wants something accessible (and won't take a lot of time away from teaching the content of the course); b) we have a site license for ESRI and have set up enterprise login, plus AGOL has the ability to allow work on maps in small groups; c)  the StoryMaps templates will look nice as final projects.

Since there has been so much change in Chicago in the 20th century (urban renewal, major highways, clearing neighborhoods to build the U of I), we are thinking of using Sanborn maps as the basemaps for this project so that the students can work with something closer to the actual geography of the earlier 20th century than modern basemaps show.  We did find a source from the U of I that has the Sanborn maps for our study area digitized and available for download as jpegs.  Yay!

So I georeferenced the image of a sample page and was able to create both a hosted service layer and a tile layer which can be added to the web map for a Map Tour and indeed, does appear on the right-hand side over the default basemap.  But then I noticed that I can only zoom in to a certain level (about 1:9000).

I opened a case with ESRI to see if there was any way to get to, say 1:500 so that students can zoom in and easily see individual buildings.  It seems that the only way to do this involves tiling so that the layer will take over 6 GB to display.  That seems like a lot of storage that we'd have to "pay" for from service credits, plus we would need four or five of these Sanborns for all the groups in the class.  Then in my last communication with ESRI, it seems that adding these additional scale levels would require us to create a custom map rather than one of the existing Story Maps, so that's an additional level of complexity we were hoping to avoid.

So, my questions to you-all are:  1)  is there any other way to add a georeferenced image to the basemap of a Story Map that wouldn't require huge amounts of storage or creating a custom map; and 2) does anyone have any other ideas of how to approach this project other than using ESRI Story Maps?

Thanks for any insights and/or experience,

Deborah Reichler

Hamilton College