Has anyone ever attempted to list all the various state traffic control policy documents?
KY -- https://transportation.ky.gov/Organizational-Resources/Policy%20Manuals%20Library/Traffic%20Operations.pdf
Arizona's supplement to the 2009 MUTCD PDF: https://azdot.gov/sites/default/files/2019/07/arizona-supplement-to-the-manual-on-uniform-traffic-control-devices-2009-mutcd-edition.pdf (https://azdot.gov/sites/default/files/2019/07/arizona-supplement-to-the-manual-on-uniform-traffic-control-devices-2009-mutcd-edition.pdf)
Wisconsin: https://wisconsindot.gov/Pages/doing-bus/local-gov/traffic-ops/manuals-and-standards/wmutcd/wmutcd.aspx
The Caltrans MUTCD supplement is pretty well known due to the cutout State Route and US Route shields:
https://r.search.yahoo.com/_ylt=Awr9Dum7wWViqIIArXlx.9w4;_ylu=Y29sbwNncTEEcG9zAzEEdnRpZAMEc2VjA3Ny/RV=2/RE=1650864699/RO=10/RU=https%3a%2f%2fdot.ca.gov%2fprograms%2fsafety-programs%2fcamutcd/RK=2/RS=QzxUpjxZNNDaAI60MkQcQ1ssB3U-
The master list is at https://mutcd.fhwa.dot.gov/resources/state_info/index.htm
There are a lot of links on the Wikimedia Commons licensing page: https://commons.wikimedia.org/wiki/Commons:WikiProject_U.S._Roads/Licensing