Functional classification, governed by federal guidelines, is the process by which roads, streets and highways are grouped into classes according to the character of service they are intended to provide. It defines the role that any particular road or street should play in serving the flow of trips through a highway network. Functional classification progresses from a lower classification handling short, local trips to a higher classification as the trips become longer and connect regional and inter-regional traffic generators. Functional classification is used in transportation planning, roadway design and determining the funding eligibility of transportation projects.

The functional classification maps are periodically updated to reflect changes in land use or travel patterns. They are also updated every ten years to coincide with the U.S. Census revisions of urban boundaries.

The functional classification map links are divided into Missouri Department of Transportation's seven districts and subdivided into rural and urban.