Hello & Welcome to Just Answer,
Sorry I didn't see your question earlier and to hear of any issue you are having with your GPS.
May I ask:1) The FULL Model Number of the device you are working with?2) The AGE of the device?3) WHEN this issue first began or was first noticed?
4) Can you confirm your question of
"If looking for an address on a state or US route why can the garmin find the address?
NOTE: I added the BOLD to find out if you meant can't?
5) Can you supply a SAMPLE address that can't (or can) be found, including the city and state?
NOTE: It does NOT have to be an actual address you are looking for, but perhaps something near by would be good. That way I can try it on one of my devices and see what comes up.
I see it has been a few days and I just wanted to follow up to see if you have any more questions concerning this issue or if the issue was resolved.
I look forward to any further questions or results that you may have.
Thanks, ***** *****