This is an interesting article on Slate that describes in short how the Mormon church grew. It mostly focuses on the economics side of the church, but it is also a nice succint history lesson as well.
But even the most devout Mormons in Africa and Latin America can only provide a fraction of the church’s annual tithing revenues. Which is why, as the Mormon population outside the United States rises—and as demands for temples, meetinghouses, and other church resources in the global south rises—the church may find it has backed itself into a corner. It has closely bound Mormon faith to the tastes and mores of the American middle class. As its growth outside the United States continues, the costs of such things will be considerable. Hence, it appears, the church’s investments in real estate and shopping malls. Eventually, as has happened already to Roman Catholicism, Pentecostalism, and Methodism, Mormonism will become a religion of the global south. And when that shift takes place, the money to keep the Christmas lights on in Temple Square will have to come from somewhere.
In general, it seems as though the big hierarchical religions are moving towards areas below the equator. Which are areas that are typically more economically unstable than the West.