What field does the Organizational Calendar Events Rule Builder State (work location) derive from?

What field does the Organizational Calendar Events Rule Builder State (work location) attribute reference?

I am building rules to be used in the creation of Calendars through the Organizational Calendar Events workspace. As I do so, one of the Attributes that I can chose is the State (work Location). However, when I look at the options available (and see many that are not available that I would expect to be there), I am wondering where the list of options is deriving from.

My first guess is that these would be coming from the REGION_2 field in the Location's address, but that doesn't seem to be the case.