symbolizing numerous categories

[FentonCheng_-_DIT]

How would I symbolize approximately 70 categories on a map? This is for citizen reported issues (311). I'm thinking of combining similar categories together, but the previous map still had 15 categories and was not ADA compliant due to the icons used.

[ThomasHoman]

This is a huge topic impacting most people. Lots of research, learning, and effort will be necessary. Have you checked out the esri resources on accessibility for insight? https://www.esri.com/en-us/accessibility/resources 

For your case, is there any way you can distill the 70 categories to 5 major topics for color control, then use object rotation and perhaps interior hatching to break things down further.

[BrandonA_CDPH]

I struggle with this sort of thing as well. I came here to suggest something similar to what @ThomasHoman suggested.  I will sometimes use two or more attributes of a symbol to symbolize a specific item (ex all water samples are drops and soil is a bag of dirt - then I use something like outline style to define different specific types of water or dirt sample) - I don't know if this is necessarily accessible though.

I wonder if you could use a single letter code rather than a symbol - would that make it more accessible (I don't know)?

I'm following to see what others come up with. Interesting question.

[FentonCheng_-_DIT]

This is what I came up with after reading both responses.

Shapes are city departments, colors are issue types. I'll need to try different colors for the accessibility side as this was just a quick prototype to test the service within the viewer app (using Javascript SDK directly, not ExB).