In Mormon 2:16 it says that in the 345th year, the Nephite armies began to flee from the Lamanite armies (supposedly from the location of the land of Joshua) "until they came even to the land of Jashon." If:
(1) "the city of Jashon was near where Ammaron deposited the records" (Mormon 2:17);
(2) the hill Shim was where the records were (Mormon 1:3);
(3) the last recorded site of the Nephites before Mormon turned 24 and retrieved the plates was "in the land of Joshua, which was "in the borders west by the seashore," where the Nephites tried to gather (Mormon 2:6-15); and
(4) the hill Shim was near the hill Cumorah, and one went "eastward" from there to a "seashore" (Ether 9:3);
then, according to a hemispheric geographical Book of Mormon model (North America--South America), Mormon (after already making a round-trip to retrieve the plates) could have been forced to make another 3000-4000 mile continuous retreat with all his people from a location on the Pacific coast ("in the borders west by the seashore") to somewhere near the hill Cumorah (New York State) and an "east" sea (possibly the Atlantic). Depending on the location of the city of Jashon, this trip would have been two or three times as far as Brigham Young led the saints. I doubt such an extensive retreat, plus another retreat "northward to the land of Shem," took place in the space of one year (Mormon 2:20,22). [Alan C. Miner, Personal Notes] [See Geographical Theory Maps]
Geographical [Theory Map]: Mormon 2:16 The Nephites Flee to the Land of Jashon (345 A.S.)