The loose meat sandwich is the only American ground-beef sandwich that is not pressed into a patty, and that refusal is the entire identity. The beef is browned and broken into loose, seasoned crumbles and never compacted, so it goes onto the bun as a pile rather than a disc. Because it has no patty to hold it together, it cannot be picked up cleanly the way a burger can, and the format admits this openly: it is served with a spoon, and the spoon is not an apology but a structural feature. This is a sandwich engineered around the texture of unbound meat, where a burger is engineered around the integrity of a bound one.
The craft is in the cook and the seasoning. The ground beef is simmered or steamed as it browns so it stays moist while it crumbles fine, never cooked dry and never mashed into a cake. It is seasoned simply, usually nothing more than salt, pepper, and onion, because the point of the build is the clean taste of loose beef rather than a sauce-driven flavor. The crumble is kept just wet enough to hold together in a mound without becoming a sauce, which is the line that separates it from a Sloppy Joe: a Sloppy Joe is bound by a tomato sauce and eaten as a wet sandwich, while a loose meat sandwich is dry-crumbled beef whose moisture comes only from its own fat. The bun is a plain, soft hamburger bun chosen to absorb that fat without falling apart, and the dress is restrained to the basics, pickle, mustard, raw onion, applied as a sharp cold counter that does not turn the beef into a sauced filling.
The variations are mostly a matter of region and seasoning rather than structure. The Iowa tavern build keeps the beef clean and unsauced and runs it with pickle and onion; the Maid-Rite chain reading is a specific, codified version of the same idea served from a steam well; the Sloppy Joe is the close relative that crosses the line into a sauced, bound filling and reads as its own sandwich. Each of those deserves its own article rather than being crowded in here.