Two big (and little-known) sources of identity theft:

(1) medical facilities. Tampa, Florida is the epicenter of this type of theft; fraudsters get their own people hired into medical billing offices at hospitals and medical practice groups to grab as much as they can. When I worked for a tax preparation service near Tampa, each person in our office dealt with more identify theft claims per year than my mother's 12-person office in Detroit.

(2) parents. There was a rash of parents using their children's social security numbers to get credit back when the economy fell apart 7 years ago. This is a consequence of assigning SSNs to newborns (which was done to prevent tax fraud), and most of the children won't find out what mommy and daddy did until they reach age 18 and can't get loans.