I always thought How the West Was Won captured the sense of the westward movement as an unstoppable migration that rolled over everything in it’s path.
The absolute worst in my memory was China Syndrome. There are worse I’m sure but I’ve not seen them.
FWIW, the train scenes in the desert with the fight scene on the logs was filmed using a locomotive of the Magma Railroad and most of the film footage was shot behind the high school in Superior, AZ. I had graduated from that high school and was working at the mine and waiting to be drafted at that time. The steam locomotive was in use until 1972 when the local smelter with it’s machine shop was closed (parts for the locomotive all had to be fabricated).