I would be careful about citing a fictional example of an American bank.

I'm not even objecting to the fiction. But more that American unit banking was extremely weird. Basically, many states banned banks from having more than one branch. The result was the world's most fragile financial system.

See https://www.alt-m.org/2015/07/29/there-was-no-place-like-can... for a comparison of 19th / early 20th century Canadian and American practices.