A link to this thread has been added to the Tennessee (US)#State Agencies RR Wiki page, so more people can learn about this.Here's a copy of the THP 10-codes & Signal codes. This has been current for years. Good luck getting a copy of unit numbers and assigned counties. The closest I was ever able to get was a list of troopers and their ranks, but no unit numbers. THP said that list of unit numbers is not public information.