Cast iron production in the USA spans nearly 300 years, and there were a lot of small cast iron makers who went out of business or their factories literally burned to the ground. Because of this, there are quite a few cast iron pans out there that are unknown and we don't know exactly who made them. These unknown cast iron pans are actually rather common, and they can be found no matter where in the country yo're looking for cast iron. One popular theory among collectors is that some of these pans were produced by prison labor, as prison work programs allegedly produced large numbers of cheap cast iron pans. However, this theory hasn't been proven because no one has found any actual business or sales records indicating cast iron pans being sent from prisons to suppliers. One unknown cast iron pan seen in different places is this huge #16 sized cast iron skillet, which weighs nearly thirty pounds and is a real monster of a pan. For decades no one was able to identify it, and they thought it was made in a prison somewhere, until one of these pans was finally found with a manufacturer's mark.