http://www.wisconsin.gov/state/index.html

This is the worst state website I have ever seen, this is what a search for "firearms" brings up.

...Wisconsin law does not allow any person who is not a peace officer to carry a firearm....

4. CAN A LOADED FIREARM BE TRANSPORTED IN A VEHICLE?

In certain circumstances, a loaded firearm may be transported in a vehicle. The firearm must be in plain view. If it is a handgun, the firearm must be in a holster in plain view. If it is other than a handgun, the firearm must be in a device inside the vehicle which prevents an unauthorized person from removing the firearm from the locking device and which is in plain view. Please see RL 34.011.


http://drl.wi.gov/prof_practice_faq_all.asp?profid=93&locid=0

This is in reference to "Working" as a private security guard or private detective. It does not apply to that average citizen, even though it says that it does. This is the list of licensing requirements for being a P.I. or a Security guard. It is really stupidly written though, I do agree. But it does not apply to open carry for the average person.