Book of Mormon setting: Overview

The Book of Mormon narrative originates in 600 BC Jerusalem. A group led by Lehi and his wife and family left Jerusalem, traveled to the Arabian coast, and then set sail for their promised land across the ocean.

Because the text of the Book of Mormon does not use modern geographical terminology, there are differences of opinion about which direction they traveled and where they landed.

In the diagram below, the black line shows Lehi's route from Jerusalem to the Arabian coast. From there, the red line shows a traditional route with Lehi landing in Chile. The orange line shows a route to Central America. The yellow line shows a route to North America.

(click to enlarge)

After evaluating the relevant extrinsic and intrinsic evidence, we conclude that the yellow line route to North America is the most plausible. It is the only route from the Arabian peninsula that has been replicated with 600 BC technology. It makes the most sense in terms of available resources, as well as ocean and wind currents.

Plus, it satisfies the historical and textual guidance. 

The historical record establishes that Joseph Smith and Oliver Cowdery identified the Hill Cumorah, mentioned in Mormon 6:6, as the same hill where Joseph obtained the plates from the stone box constructed by Moroni. This was also the site of the repository of Nephite records, which were subsequently moved to an unknown location, apparently "not far from" Cumorah.

Using the New York Cumorah as a "pin in the map" leads to a variety of possible settings. Rejecting the New York Cumorah opens the possibilities to the entire world. 

(Some people claim the events happened in "the Americas" or the "Western Hemisphere," but the authoritative sources for that claim also claim Cumorah is in New York, so rejecting the constraint of the New York Cumorah logically and necessarily rejects the constraint of the Western Hemisphere.)

Using Cumorah as a pin in the map (and deeming D&C 125 as a revelation of the location of Zarahemla) leads to this general map for the bulk of the narrative (from Mosiah through Moroni). this setting developed after Lehi landed in Florida, presumably along the panhandle, Nephi escaped to Tennessee, and King Mosiah led the people to the land of Zarahemla in modern-day Illinois.

This map is consistent with the geographical information in the text, the teachings of the prophets, and relevant archaeology, anthropology, geology, and geography.

For a good overview of alterative theories, see https://bookofmormon.online/map/internal