The Dominance of Female Early Voting

This is an interesting phenomenon. I haven't been around politics long enough to know if this is a normal pattern for Memphis. There is a huge number of precincts that have over 2/3's of early voters being women. The question I have is why? Is it because of differences in employment, apathy, poverty, lost voting rights? After the election I'll make an updated map to see if the pattern still holds.