The commercial calculation that had made her invention attractive was not sufficient to overcome the racial prejudice that governed the business dealings of the time.

This rejection is a specific event in Mary Kenner’s life, and it is also a general pattern in the history of Black American inventors.

The gap between holding a patent and seeing an invention become a product has, throughout American history, been a gap that race made dramatically wider for Black inventors than for white ones.

Patent protection, when it functions as designed, protects an inventor’s legal rights — no one else can manufacture or sell the patented design without the inventor’s permission.

But the patent system does not force anyone to manufacture a product, does not compel anyone to do business with an inventor, and does not prevent the kind of racially motivated rejection that Mary Kenner experienced.