Vintage Truck: 1904 Knox-Martin Tractor – The First Semi Truck Tractor? Certainly The First Three-Wheeler Semi Truck Tractor?

The 1904 Knox-Martin tractor is quite the beast. Here’s what they had to say about it:

“Handling a big load with the Knox-Martin Tractor is a simple proposition. It will save you money and relieve you of a lot of worry. “

So is this the first semi-truck tractor? Maybe not, but more likely the first with three wheels. Here’s a shot of the major benefit of its fifth fourth wheel: