At the bottom right corner of Columbia back covers is usually a numeric code:
WB (quoting Bruce Spitzer) , BeatleFan, Perry Cox, these identify the following LP cover manufacturers:
2 Imperial Paper Box Corp., Inc. of Brooklyn, NY .
3 Modern Album of Long Island, NY
4 Imperial Packing Co., Inc. of Indianapolis, IN
5 Modern Album of Terre Haute, IN > Los Angeles
6 Imperial Packing Co., Inc. of Indianapolis, IN > LA or Winchester
7 Columbia 1969 (original or subsidiary label)
8 Decca? c. 1966
9 Modern Album of Terre Haute, IN > Jacksonville, IL
Source: WB on Hoffman thread
.There is a 1 code missing from the list ( pictured below).
We know KoB promo was pressed in 1959, the jacket manufacturers are local to the plant, we know: 2. Imperial Paper Box Corp, Brooklyn NY; 4. Imperial Packing Indianapolis, 6. Imperial Packing when supplying West Coast pressing plants.