The Highway layer is composed of the following sub-layers:
- Expressways - dark pink lines
- Primary Highways – orange lines
- Secondary Highways – dark green lines
- Regional Highways – light green lines
- Local Routes – dark brown lines
These layers comprise the entire US highway network, including multi-lane freeways, interstate highways, parkways, and any ramping connected to each.
Note: In all the highway layers, a new field called Shield Code has been
added in StreetPro Display United States. This field contains a 4-digit integer
value that is a unique code for Highway Shield icons.