Can I carry a weapon in my personal vehicle while using it for the USPS?

I work for the US Postal Service running a rural route in Wisconsin. As part of this I use my personal vehicle, not a postal vehicle, to run my route. Would anybody be able to tell me if I can legally carry a firearm in my vehicle (not on my person) while running my route?(Edit: Grammar) via /r/CCW https://ift.tt/3ebilEm