If there is such a law and there isn't in my state but more to the point, then why are many roads too narrow for two motor vehicles to pass without one going off the shoulder and into the "Ditch". The standard approach to these situations is the car stops as far right as possible and the pickup going the other way rides off the road to scrape by.
If cyclists would ride single file as required by law, I could pass without going off the road. Pretty damned simple.
I'm having a hard time understanding this. There are roads where you live on which two cars do not fit? Maybe you shouldn't be allowed to drive a vehicle that is wider than one lane down those roads then, eh?