I've got an entire page of boxing postcards:
https://imageevent.com/exhibitman/boxingpostcards
Some good info there, some dumb mistakes too.
Greg, here's the master set of the Benham Indian PCs of Jeffries:
My personal favorite is the one on the farm here in Burbank:
Here's a cabinet photo of Jeff on the farm from his personal collection:
This is the earliest boxing PC I have:
My only JJ PC:
I do like 'em postally used. Not only does it keep prices down due to condition , I love the sense of history and provenance.
A few French hand-tinted ones from the HB series:
Alfred Noyer published a lot under his "AN" mark. including this one of Dempsey and Tom Mix on the lot at Universal:
Here is the studio photo he used:
Bit o trivia: the building there was later used as the Bates Motel.