For bourbon, rye, wheat, malt, and rye-malt whiskey produced on or after March 1, 1938, Regulations No. 5 required storage in charred new oak containers as part of the federal type definition.
Verified against the complete official amendment, F.R. Doc. 38-628, at 3 Fed. Reg. 561–563.
Corn whiskey was treated differently, and the amendment did not itself prove why the agency selected the new-oak rule or which regions benefited. Earlier 1936 regulations had already tied recognized age for American-type whiskey to new oak.
The operative regulatory language expressly applies to production on or after March 1, 1938 and lists bourbon among the types required to use charred new oak containers.
Use for the date and legal requirement. Keep regional-benefit and lobbying explanations in separate interpretive claims until independently corroborated.