to: ALL
I've been trucking about 20 years, and it used to be illegal, under federal rules, for truckers to carry firearms in the cab/sleeper. About 5 or 6 years ago however, this part of the regs was quietly deleted.
I don't have one of the old books around anymore, so I can't cite the old rule but I went just now and looked at the new reg book, and there is still no mention of firearms carry one way or the other. It's just possible that Part 49 may in someway address this issue, but it mostly deals with Hazmat regs so I doubt it...I'll have a look.
Bear in mind that these are FEDERAL rules, not state laws. State laws may be different although many of the states pretty much adopted the federal laws.
I would consult a lawyer, but the federal rules (Part 355) mandate that states follow them while a truck is on any part of the federal highway system or within a certain distance from it, or while engaged in activities such a getting fuel, repairs, sleeping and delivery.
Like one of the other posters, I have carried for years (even when it wasn't legal) and always will. I have twice been in the unfortunate position of having to defend myself with a firearm while trucking, and the firearms presence quickly defused the situation and allowed me to escape unharmed.
If in doubt, call the 800 number for a particular state DOT office and ask them to cite the rule for you.