Disney had a very backwards way of building the Matterhorn. They built the mountain first, had the exterior completely planned out then Disney imagineering was given the quest to do the problem solving of building the roller coaster inside of the already existing footprint of the mountain. One would normally think you would build a roller coaster and then build a mountain around it. Since it had never been done before they did it the opposite way.
Disneyland's Matterhorn is 100th scale of Switzerland's Matterhorn which sits 14,700 feet in the air. Disney's Matterhorn is 147 feet and made up of over 2100 steel girders that make the frame and give mountain its strength. Nearly all 2100 were different sizes and lengths to create this jigsaw organic looking mountain.
The a very well hidden 15 story building's exterior was originally made out of plywood that was then painted and sculpted on the outside. That left for Aero development and Disney imagineers a very intricate puzzle of space to try to put in not just one, but two roller coaster tracks! Admiral Joe Fowler knew that this would be something that would be in high demand and he also knew that Disney could use a lot more capacity for guests at Disneyland. Putting in two tracks theoretically would mean twice as many guests could enjoy Matterhorn mountain.
This is something they've gotten away from in recent years with other roller coasters where they do a switch track. Instead of actually building two different tracks operating at the same time, Disney figured out that it's easier to make two different loading areas. Like what we see at Big Thunder Mountain or the Incredicoaster, by using one track and loading guests in two different locations. It's a lot more affordable than building the ride twice. And it gives you the capacity that you need because you're always loading a train or cart to get on that track.
More to come in part 5....
Growing up in Los Angeles in the 70s/80s we visited Disneyland on a regular basis and often after school, before "Annual Passes".