5-Among those informed few who vote in smaller elections, especially local ones, are those who stand to benefit materially from one outcome or another. This could be a large enough number to sway otherwise similarly matched candidates, such that whoever wins will owe favors to one group or another.
Around here, school bonds almost never lose, and school board members are often very friendly with school unions.
Interesting. This is basically what I meant by (4).
Is this the case with all such low-level elected officials, or just school board members?
I skipped October and November owing to election season, but opening back up:
As Multiheaded added, "Personal is Political" stuff like gender relations, etc also may belong here.