Mo. Rev. Stat. § 304.025: Highway and vehicle defined.

1. The word "highway" whenever used in sections 304.014 to 304.026 shall mean any public road or thoroughfare for vehicles, including state roads, county roads and public streets, avenues, boulevards, parkways or alleys in any municipality.

2. The word "vehicle" whenever used in sections 304.014 to 304.026 shall mean any device operated on highways, except those used exclusively on rails or tracks.