"No Passing Zone" pennants

[CtrlAltDel]

I think a more logical color combination would be red and white.

There is also the rare BRS (big red sign) as seen here near Corbin KY:

[peterj920]

I've never seen the white signs in wisconsin

In less developed areas of the City of Milwaukee (primarily the far northwest side) Do Not Pass and Pass With Care signs are very common. 

91st St:
https://www.google.com/maps/@43.1811115,-88.0241921,3a,75y,200.34h,67.74t/data=!3m6!1e1!3m4!1sfyVcG3D8hw8Tcijahof1-A!2e0!7i13312!8i6656?hl=en

Fond Du Lac Ave:https://www.google.com/maps/@43.1356074,-88.0346842,3a,75y,329.89h,90t/data=!3m6!1e1!3m4!1sjxQG8VNEnp6N87lAb6F2TA!2e0!7i13312!8i6656?hl=en

107th St:https://www.google.com/maps/@43.1362039,-88.0452359,3a,75y,10.7h,86.66t/data=!3m6!1e1!3m4!1sZoJnMYOSNDES8kHcgyEpmQ!2e0!7i13312!8i6656?hl=en

They even have Pass With Care Signs like on 107th St:
https://www.google.com/maps/@43.1380416,-88.0452159,3a,75y,188.68h,73.97t/data=!3m6!1e1!3m4!1seTVJW5Q3aZOv4R5PV3lQhA!2e0!7i13312!8i6656?hl=en

[Scott5114]

Oklahoma doesn't use any signs at all to denote passing zones. Just the pavement markings.

How can you tell where the begin and end in the snow?

What snow?