I love the sound of Sacred Harp music; the rest of the family is split. I was listening to quite a bit of it tonight, including an NPR story, some YouTube clips, and a documentary, Sweet Is the Day: A Sacred Harp Family Portrait.
The Sacred Harp was a hymnal (using shape notes) that went through a number of editions from 1844 to the early 20th century; it’s given its name to the genre that has included other hymnals, including Southern Harmony.
Some of the tunes are included in other contemporary hymnals (Beach Spring, Northfield, and Wondrous Love are three tunes that appear in the Seventh-day Adventist Hymnal, for instance), but in a diluted form. The tune, Northfield, for example, is used for the hymn, “O for a Faith,” in the SDA Hymnal (#533). If you know the tune, compare with this midi, or the the recording you’ll find about half way down this page–the fugue-like parts were in the old SDA Hymns and Tunes (picture below), but have been simplified in more recent SDA hymnals.