I was wondering where the term “chuck wagon” came from, so I started looking. That Wikipedia article says Charles Goodnight, a Texas rancher, introduced the concept in 1866:
Goodnight modified a Studebaker-manufactured covered wagon, a durable Civil War army-surplus wagon, to suit the needs of cowboys driving cattle from Texas to sell in New Mexico. He added a “chuck box” to the back of the wagon, with drawers and shelves for storage space and a hinged lid to provide a flat working surface.
But what was this “chuck”? I went to the OED’s chuck wagon entry (from 1933) and found it was their chuck n.⁵, which is “perhaps the same as chuck n.⁴”: “A lump; a large awkward-shaped piece of wood for burning, a chock n.¹; also of bread, meat, and the like, a chunk n.¹” (sense 2: “a cut of beef extending from the horns to the ribs, including the shoulder-piece”); unfortunately, the entry is from 1889, and the etymology is simply “apparently originally the same as chock n.¹” So we go to chock n.¹ “A piece or block of wood; a log, a stump”; this entry was revised in 2015, and the etymology is more discursive, even if it ultimately wanders off into a swamp:
Apparently < Middle French (northern) choque (also chouque; French regional (northern) choque, chouque), apparently originally a variant of soche, souche log, block of wood (11th cent. in Old French in Rashi as çoce; French souche), further etymology uncertain and disputed; compare Italian ciocco log, block of wood (14th cent.).
I don’t know how you get choque, chouque from soche, souche, but it looks like that’s the best that can be done for now. (In case you’re wondering, they didn’t serve chuck steak at a chuck wagon: “The meats were greasy cloth-wrapped bacon, salt pork, and beef, usually dried, salted or smoked.”)
Green’s has “chuck” from 1837 (and the unrelated? “tuck” from 1835).
OP: I was wondering where the term “chuck wagon” came from, so I started looking. That Wikipedia article says Charles Goodnight, a Texas rancher, introduced the concept in 1866:
I was expecting this to be the actual explanation.