California also has that law: https://leginfo.legislature.ca.gov/faces/codes_displaySection.xhtml?lawCode=VEH&sectionNum=21656 https://leginfo.legislature.ca.go

California also has that law: https://leginfo.legislature.ca.gov/faces/codes_displaySection.xhtml?lawCode=VEH&sectionNum=21656 https://leginfo.legislature.ca.gov/faces/codes_displaySectio.... Also Alaska (http://www.legis.state.ak.us/basis/statutes.asp#28.35.135 http://www.legis.state.ak.us/basis/statutes.asp#28.35.135) Also Colorado (http://law.justia.com/codes/colorado/2016/title-42/regulation-of-vehicles-and-traffic/article-4/part-11/section-42-4-1103 http://law.justia.com/codes/colorado/2016/title-42/regulatio...) And Montana (http://leg.mt.gov/bills/mca/61/8/61-8-311.htm http://leg.mt.gov/bills/mca/61/8/61-8-311.htm) Seems like a common regulation in certain states, particularly those with a lot of mountain terrain. (It is often not feasible in any circumstance to pass on the left on a mountain road, so I can see why these regulations popped up.).