The web site www.poi-factory.com has published a report showing how many states have laws on their books against those GPS devices you stick to your car windshield.
Turns out, Oklahoma is one of them.
No person shall drive any motor vehicle with any sign, poster, other nontransparent material, or debris, including but not limited to snow, ice, or frost, upon the front windshield or the side wings, or side or rear windows or suspend any sign, poster, object, or other material from the interior of the vehicle which materially obstructs, obscures, or impairs the driver's clear view of the highway ahead or to either side or of any intersecting highway.
According to the web site that means mounting a GPS unit on your windshield when you drive is illegal. You could end up getting a ticket.
Only fifteen states actually allow those mounted devices, according to the web site.