The scale of Hyatt's collection is the reason it dominates the field: thousands of interviews, recorded verbatim, from people describing their own practice in their own words. Nothing comparable exists for any other American folk-magical tradition, and much of what is known about regional variation, about the economics of conjure, and about how practitioners understood their own work rests on it.
The conditions under which it was made are inseparable from what it is. This was the Jim Crow South. A white clergyman with a recording machine was asking Black practitioners about a practice that had been criminalised, ridiculed in the press and treated by white authorities as evidence of backwardness. What informants chose to tell him, what they simplified, what they withheld and what they may have invented for a paying stranger cannot be recovered from the transcripts. Hyatt also transcribed phonetically, rendering his informants' speech in an eye-dialect that presents Black American English as a deviation from a norm, a convention now widely criticised for what it does to a reader's sense of who is speaking.
None of that makes the collection worthless. It makes it a source that has to be read with its conditions in view, which is true of every ethnographic record and is simply more visible here.
The operative content of the record, the formulae, the preparations and the procedures, is not reproduced in this atlas. That is partly a rights matter, because Hyatt's volumes are in copyright. It is more importantly a question of what this material is. Hoodoo has practitioners now. Its working knowledge belongs to them and to the communities that carried it, and an encyclopedia that hands it out has decided that being interesting to outsiders outweighs that. The atlas records what the tradition is, who documented it, and under what conditions, and stops there.