In Missouri, open carry can be modified by local ordinances. So all across the state of Missouri, you can have additional local ordinances that you must also be aware of.
God help me for saying this, but the ONE GOOD THING Illinois did was shoot down (no pun intended...) an amendment to IL's conceal/carry law that would've enabled each municipality to set their own requirements.
In doing so they also struck down Chicago's anti-handgun restrictions in the process.
That'll be ONE THING the Illinois State Legislature and this Governor got right in the last 35 years I've lived here.
I'm aware, ST, but what that means is: either there IS no local ordinance restricting Oklahoma teenage girls from open carrying; or this cop should have cited and disarmed them on the spot.