I’ve heard it ties back to WWII railcar dimensions and the GMA standard, but I can’t pin the year. I’m updating a 30-minute onboarding module for new warehouse hires, and fun, accurate origin stories help skills stick and support retention — does anyone have the real backstory or a solid source?
Mostly stuck because it fits two-across in a 96" trailer and the grocery case math works — think 10"×12" cartons laying out cleanly on 40×48. For your 30-minute module, show that “two-across” visual and note CHEP’s U.S. pool in the ’90s helped cement it; ISO 6780 also lists 1219×1016 as the NA size (Pallet - Wikipedia). @patwill is right on timing, but the trailer width + case pattern geometry is the practical why.
A good breadcrumb is the DoD: ‘MIL-STD-1660 (Design Criteria for Ammunition Unit Loads)’ calls for 40x48, and grocery later standardized around it while 42x42 and 48x48 hung on in drums/chemicals. Want the clause citation from 1660? For training, a tiny timeline — WWII palletization → DoD 40x48 → GMA codifies — tagged ‘from foxholes to frozen foods’ lands well.
Building on @adams55’s point: MIL‑STD‑1660 (1978) normalized 40×48 for ammo, GMA codified it in 1988, and CHEP’s 1990s pooling made that footprint unavoidable. For your onboarding deck, you can shorthand it as ‘WWII → DoD ’78 → GMA ’88 → CHEP ’90s’ and drop this read: Pallets: The single most important object in the global economy.. Caveat: ISO 6780 (1988) pushed 1000×1200/800×1200, but the US was already too locked into 48×40.