Route 172 was created as part of the 1932 state highway renumbering from a previously unnumbered road.

The portion in West Springfield, which was not state-maintained, became an unnumbered road.

Several unnumbered roads also are maintained by the state, including:

State Highway 95 began as an unnumbered farm-to-market road.

Route 125 was established from a previously unnumbered road in the 1932 state highway renumbering.

Past this intersection, Main Street continues as an unnumbered road into the center of town.

Chouteau Trafficway continues north of I-35 as an unnumbered road.

Independence Boulevard continues north as an unnumbered road onto the military base.

Route 100 becomes an unnumbered road in Massachusetts.

Before 1927, what is today Route 79 was an unnumbered road.