I thank reader Mary for that excellent analysis of the corporate decision-making process. I figure that in Randworld (the alternate universe that ATLAS SHRUGGED is set in) businesses are smaller, and thus able to be run by single people, families, or a small group of people. She mentions only one multi-national corporation and that, too, is run by a single family, generation after generation. This page has the first mention of "Rearden Steel," which is personally run by one of the heroes of the book. Rearden Steel, heroic as it is, is probably much smaller and more local than something like U.S. Steel.
I'm currently reading a book about Rand, "Goddess of the Market" by Jennifer Burns. It contains a lot of information I didn't know about the author, especially her involvement with American politics. I haven't gotten to the part about ATLAS yet, but it should be enlightening.