There are a couple possibilities to my mind. Do you happen to know where North 40 gets their chicks from? That would likely answer what exactly this chick is.
My first thought was Crevecouer. Murray McMurray has those and they seem like the most common solid Black crested breed to get from a feed store-type setting. This chick is at that awkward age where it's hard to tell for sure if they have a beard or not, but if it is bearded, I would say it's a Crevecouer.
I know of at least one hatchery (I believe Meyer) who sells BBS Polish that are not white-crowned, so the other possibility is a solid Black Polish from them. If this little one is clean-faced, I would assume that it's a Black Polish instead.
Brabanters come in solid Black, but that's such a rare variety... This chick has a bit too much crest already for a Brabanter, and it's slicked back rather than pointed like a Brabanter's crest would be, so I really don't think it is a Black Brabanter.
