The Mysteries of Pit Beef

Maryland has given the world three great treasures: steamed crabs, Dashiell Hammett, and apparently, pit beef.
I say apparently because, over the past few years, I've read some write-ups on the subject and none of them ring quite true to me.
First off, let me tell you what pit beef is: it is beef, grilled outdoors, sliced thin. It is charred on the outside and pink on the inside. It is served on cheap white bread with copious amounts of horseradish & mayonnaise. Think of it as grilled roast-beef.
Let me tell you what pit beef is NOT: it is not dry rubbed, it is not well-done, it is not served on a kaiser. (Though, if you like it that way, that's fine by me.)
The writers all seem to think it is a recent invention, maybe 20 years old, but I remember pit beef from my childhood in the 60/70's.
It was, back then, often part of a fundraising activity known as a "bull roast." Bull roasts were (are) often held at volunteer fire halls, churches, or in fields. There are bull roasts (summer), bull & oyster roasts (months with R in them), and ham & oyster roasts too.
A proper bull & oyster roast always served fried oysters, raw oysters, crab soup, potato salad, macaroni salad, steak tartare, sausage, and of course, pit beef. These events were usually, but not always, catered.
Tickets to a roast always had the menu printed on the back. It made it that much harder to resist, especially since the roast went on for hours and hours, and was all you could eat. Oh, and there was beer too - lots of it.
Later it seemed, the late 70's or early 80's, pit beef came into a more permanent form as roadside stands, often located in a bar parking lot, and usually open on the weekends only. Today there are pit beef establishments open 7 days a week. Some of them are very good, some aren't: you have to search for the good stuff.
That's what I know about pit beef. If your recollections differ with mine, or you can place the origins of pit beef back beyond my memory, please leave a comment.

A typical roadside pit beef set-up. Note the grill is made from a furnace oil tank. The diesel stacks are a nice touch.

The real thing: ask for no more, expect no less!