Posted By:
PaulI don't think there can be much debate. It's the 1937 O-Pee-Chee. Some might point to the R-314 Canadian Wide Pen premium which for many years was considered a 1936 issue. But it's been pretty conclusively shown that the Canadian Wide Pens were issued in 1937 at the earliest, and possibly later. Plus, a lot of people don't consider premiums cards.
You'll often see Feller's 1938 Goudey or even his 1948 Bowman advertised as his rookie. But that's just plain wrong. The 1937 O-Pee-Chee is obviously earlier.