PSA Graded Cards T206 question

[Mountaineer1999]

Looking through the POP Report for the T206 they are broken out into the different backs. But what are the Unknown Backs? There are 61,522 graded with an Unknown Back.

[steve B]

Those are the ones done before they started keeping track of backs.

Steve B

[Mountaineer1999]

Oh... OK. That makes sense. Thanks Steve