This maybe a rule you didn't even know existed.You might know have known since may GPS and cellphones offer them as an option --or right out come with one. I am talking about the windshield suction cup holder which in Maine -- and many states -- is illegal. The fact is, according to ProClip, this practice is illegal in more states than it isn't. It just isn't enforced very often ... yet.

So where can you mount it legally? There are dashboard mounts that are legal and I have a friend that has a clip that uses her air vent as a holder. There are also adapters to make your windshield holder into a dashboard holder.

Here is a great video that outlines all the states and their laws about cellphone use while driving.