If you have a mac and still want to use Dave's Redistricting then here is the solution:
https://ftp.mozilla.org/pub/firefox/releases/52.9.0esr/mac/The last version of Firefox to run Silverlight (52 ESR) can be downloaded from the link above. Simply select en-US for American english and en-GB for British english. Then click on the link to download.
After downloading and installing Firefox you still have one thing to do. Click on menu (right-most button with 3 bars), and open preferences. Open advanced settings and click on Update. Then check the box "Never check for updates (not recommended: security risk)". Otherwise, Firefox will automatically update to 60.2 ESR, which doesn't allow Silverlight.
