I should expect that many songs from that segment of society wouldn't have been cast (on their face) as slavery songs, so much as what I'll call "We won't let them take our rights away!" songs. The addition of those songs, along with State's-rights songs, to the pro-slavery songss as such, would make the total much greater.

And I'd expect that songs which were on their face "rights" songs might   include a higher percentage of creditable songs than the pro-slavery songs as such, even though the underlying intention might be seen as the same.

Dave Oesterreich