Hi All. I came across this the other day. Rather well travelled (it landed in a schoolboy album in the UK in the 1930s) #304, but with what looks like a plate crack down the right margin. Is this what it is?
Johl 'US stamps of the 20th Century' Vol. 1 p.69 (the only reference I have to hand) seems to refer to a similar crack. Hope the scans show it OK. Thanks.