The project D. Building the Transcontinental I believe is the one that led to the creation of a system of time zones across America
History is his story I think that's the answer. Just playing though
A hogan is more of a permanent home, it takes a lot more time and materials to build. The Navajo are people that had kept sheep and goat, they mostly lived at between 5000 and 8000 feet in elevation. Some apache did make make hogans but they also used tipis. Apaches live a more mobile life style so other types of houses were more useful.
