Born, raised, and currently reside in the suburbs of Detroit. Both my parents were born and raised in Detroit. They both have fond memories of what Detroit used to be in the 40s-early 60s (my Dad is 82 and Mom 75 to give you a time reference). Parts of Detroit are on their way back but it is, generally, as bad as its rep I hate to admit.
As for knife laws, a folding knife with a blade over 3" can be considered a deadly weapon although they would have to prove intent on your part. To avoid any potential problems, I carry a knife with a blade 3 or under, usually a Delica FFG, Mini Grip, or SAK.