I've noticed in New Jersey for the iPhone client, we get shields for some of the US routes that are labelled "US Hwy." Most of the state routes I've seen on the map do not produce shields as they seem to be labelled "State Rte" (instead of "State Hwy," maybe?). This is a problem because all numbered roads in New Jersey are referred to as "Routes" and not "Highways" and really should be reflected as such in any regionally savvy navigation system. This is because many of these routes are simply marked out over old, local urban roads and calling them highways misleadingly implies that they're some kind of fast way to get somewhere.
It seems also that, with divided roads, when we put the N, S, E, or W suffix in the name to indicate direction, the iPhone client does not produce a shield. Also, dual-signed roads: "I-95 / NJ Turnpike" does not produce a shield in the iPhone client as well.
Wazing the Garden State... one jughandle at a time.AM: Central New JerseyDayton, NJ USA / AT&T iPhone 5 / iOS 6.1.4 / Waze 188.8.131.52