Packing plant branch houses took in carcasses and shipped out processed meats. Think of steaks and chops for restaurants, hamburger for McDonalds, bacon and bologna for grocery stores.  The big slaughter operations all had branch houses, where further processing took place. These branch houses supplied carcasses and processed meats to restaurants and institutions, grocery warehouses, and your neighborhood meat markets.

Some slaughterhouses were also places that processed finished products, creating their brand name bologna, ham, luncheon meats, sausage, etc.

Oscar Mayer was a slaughter operation that also processed finished product. They began in Madison WIS, purchased a Kohr’s plant in Davenport IA, and later a pork operation in Perry IA.

The meat industry did undergo major changes, moving from multi-story buildings to single level structures beginning in the 30s. Electricity and motor driven assembly lines made this possible. But many existing structures remained in use up into the 70s, where their inefficiency became too costly to maintain, combined with growing demands of the unions.

Another major change that occurred, in Sioux City and elsewhere, were brought about by Iowa Beef Processors (later IPB) who built a new plant that shipped “boxed beef” in 1958. IBP was non-union and fought the unions. Their new processing created what became known as boxed beef, because they removed the bones, fat and other waste at the slaughter house. This reduced the weight being shipped, eliminated the shipping of carcasses (and the need for branch houses), and allowed efficient loading of trucks. IBP also shipped by truck, another non union entity, which could deliver faster than rail. This change allowed fresh meat to be in the grocery store’s meat case days, if not a week, earlier. And at a cheaper price.