Regional US house rules

Descends into

• NMJL card — 1937, annual hand list

Cross-comparison

corroborated — two or more independent sources agree on the facts that define this variant

• [1] records a 1924 'American Code of Laws for Mah-Jongg' produced by a committee of publishers and enthusiasts, which unified variations before the NMJL's 1937 standardisation
• [2] describes the proliferation of incompatible American rule sets before standardisation
• [3] records that Babcock himself sat on the committee that published a standardised rule set, which is the 1924 American Code of Laws that Grokipedia describes. The pre-NMJL standardisation effort therefore involved the man whose rules it was trying to supersede

Reading it

Three sources support a distinct pre-NMJL layer: a 1924 American Code of Laws produced by a committee, the proliferation of incompatible rule sets that prompted it, and Babcock's own membership of that committee. The node is a real stage rather than a placeholder, though no source gives it tiles or a hand size because it is a period rather than a ruleset.

Sources

1. Grokipedia. "American Mahjong." cross-check checked 2026-09-18

   Jokers appearing in sets from the 1940s; the NMJL mandate from the 1960-61 season.

   https://grokipedia.com/page/American_mahjong

   Also cited on: NMJL card, American mah jongg · bibliography #17

2. Wikipedia. "American Mahjong." canonical checked 2026-09-18

   Racks, jokers, the Charleston, and the NMJL / AMJA annual card.

   https://en.wikipedia.org/wiki/American_mahjong

   Also cited on: Babcock rules, NMJL card, American mah jongg, AMJA card · bibliography #13

3. Wikipedia. "Joseph Park Babcock." cross-check checked 2026-09-18

   Biography of the populariser: 1893 to 1949, his 1920 Rules of Mah-Jongg known as the red book, and his membership of the committee that published a standardised American rule set.

   https://en.wikipedia.org/wiki/Joseph_Park_Babcock

   Also cited on: Babcock rules · bibliography #65

4. MahjongCompare. "Mahjong History and Origin." supporting

   NMJL founders (Cecil, Meyerson, Jacobs, Potter), the 1937 Essex House meeting, and jokers entering the official rules in 1961.

   https://mahjongcompare.com/history

   Also cited on: Babcock rules, NMJL card, American mah jongg · bibliography #14