March 1, 1938
United States
The rule converted an important production practice into a national identity standard, shaping maturation, cooperage demand, and the legal distinction between bourbon-type whiskies and corn whiskey.
Verified against the complete 1938 amendment. This event establishes the rule and date only. The separate interpretive claim that the rule favored particular regions or displaced refill-cooperage producers remains Researching and is not asserted here.
Federal Regulations No. 5 made charred new oak storage part of the type definition for bourbon and several related American whiskies produced on or after March 1, 1938.
Verified foundation
Regulations No. 5, Amendment No. 5 made charred new oak storage part of the type definition for bourbon, rye, wheat, malt, and rye-malt whiskey produced on or after March 1, 1938. Corn whiskey remained subject to a different cooperage rule.
Publication boundary
This event establishes the federal requirement and effective date. It does not claim that a particular region caused the rule, that the rule was enacted as a cooperage-industry subsidy, or that every producer had previously used refill cooperage.
Remaining interpretive question
The older regional-model claim remains in the Claims database as a separate Researching item until producer-level and rulemaking-history evidence establishes who advocated for the rule and how it changed regional competition.