Missouri State Highway System
In Missouri, odd-numbered highways run north-south and even-numbered highways run east-west. Missouri also maintains a secondary set of roads, supplemental routes, which are lettered rather than numbered.
[Image:Missouri 366.jpg|thumb|Route 366 in St. Louis]
Missouri has also changed highway designations with a US route or an Interstate [Highway System|interstate] with the same number is designated through the state. There are a few instances of number duplication between federal and state highways, but any such pairs of highways are nowhere near each other to avoid confusion.
In some states, highways are allowed to be discontinuous. Missouri overlaps highways in order to maintain continuity.
The Missouri [Department of Transportation] routinely uses the term "Route" in reference to the names of the roads. However, Missouri statutes define them as "State Highways". Missourians may use the terms "Route" and "Highway" interchangeably when referring to a state road.