Definitions for "Beltway"
a freeway that partially or completely encircles a metropolitan area. An example is the Las Vegas Beltway (I-215) which is currently being constructed around the Las Vegas metropolitan area.
a beltway is a freeway that completely encircles a metropolitan area. Examples include Interstate 495 around Washington, D.C., and Interstate 465 around Indianapolis, Indiana. There are not as many full beltways west of the Mississippi River.