I spotted this spelling mistake as soon as I saw this sign in Flagstaff. It’s not “Humphery St”, it’s “Humphreys St”, at least according to the U.S. Postal Service.
The sign that was there in 2011 (as seen in this Google Maps snapshot) is closer, at least displaying “Humphrey St”
As a sanity check, I checked further downstream on Google Maps and discovered that the street is indeed “Humphreys St”.