In 3 Nephi 3:21-25, we find that the Nephites gathered to protect themselves from the Gadianton robbers:
But Gidgiddoni [the commander of the Nephite armies] saith unto them [the Nephites]: . . . therefore we will prepare ourselves in the center of our lands. And it came to pass in the seventeenth year, in the latter end, the proclamation of Lachoneus had gone forth throughout all the face of the land, and they had taken their horses, and their chariots, and their cattle, and all their flocks, and their herds, and their grain, and all their substance, and did march forth by the thousands and by tens of thousands, until they had all gone forth to the place which had been appointed that they should gather themselves together. And the land which was appointed was the land of Zarahemla, and the land which was between the land Zarahemla and the land Bountiful, yea, to the line which was between the land Bountiful and the land Desolation. . . . And they did gather themselves together in the land southward, because of the great curse which was upon the land northward. And they did fortify themselves against their enemies; and they did dwell in one land, and in one body . . . (emphasis added)
It is significant here that, for the second time in the text, reference is made to a distinct "line" between the land Bountiful and the land Desolation. We find the other reference in Alma 22:32-33:
And now, it was only the distance of a day and a half's journey for a Nephite, on the line Bountiful and the land Desolation, from the east to the west sea; AND THUS the land of Nephi and the land of Zarahemla were nearly surrounded by water, there being a small neck of land between the land northward and the land southward. . . . AND THUS the Nephites in their wisdom, with their guards and their armies, had hemmed in the Lamanites on the south, that thereby they should have no more possession on the north, that they might not overrun the land northward. (emphasis added)
It is very interesting that if we place the Book of Mormon story in Sorenson's Mesoamerican setting, and if the "small neck of land between the land northward and the land southward" correlates in some manner (depending on the theory) with the Isthmus of Tehuantepec, then "the line which was between the land Bountiful and the land Desolation " might represent the Coatzacoalcos River.
Secondly, using this correlation, we find an answer to another requirement of the text. In the geographical description in Alma 22, Mormon says, "AND THUS the land of Nephi and the land of Zarahemla were nearly surrounded by water, there being a small neck of land between the land northward and the land southward." Most interpretations I have seen seem to connect this phrase only with a "west sea." an "east sea," and an isthmus ("small neck of land"). However, by including the "line" (or Coatzacoalcos River), Mormon's summarizing words, "AND THUS the land of Nephi and the land of Zarahemla were nearly surrounded by water," seem much more plausible.
Thirdly, using this correlation, we find the answer to the final requirement of the text in Alma 22:33: "AND THUS the Nephites in their wisdom, with their guards and their armies, had hemmed in the Lamanites on the south, that thereby they should have no more possession on the north, that they might not overrun the land northward." A small neck of land running along the Pacific coast of Guatemala, turning north through the Isthmus of Tehuantepec, and then turning northwest to parallel the Gulf of Mexico in the state of Veracruz has served as a primary corridor for travel and trade in Mesoamerica for millennia. Along this passageway lie numerous sites of fortification and natural defenses. By fortifying along this ancient trade route, the Nephites apparently blocked the Lamanites in the most complete and effective manner possible. The Book of Mormon geography student might contemplate the fact that while the 130 mile distance across the Isthmus of Tehuantepec appears too far for a Nephite to cover in "a day and a half's journey," the distance from the southernmost head ("from the east") of the Coatzacoalcos River to the shores of the Pacific Ocean (or "to the west sea"), would represent the maximum width of difficult fortification along this ancient trade route, and would be well within the given description of "a day and a half's journey for a Nephite, on the line Bountiful and the land Desolation, from the east to the west sea.". [Alan C. Miner, Personal Notes] [See Geographical Theory Maps] [See the commentary on Alma 22:32; Helaman 4:5-7]
3 Nephi 3:23 The line which was between the land Bountiful and the land Desolation ([Illustration]): [According to John Sorenson] the position and nature of the Coatzacoalcos River qualifies it to have constituted "the land" that, practically and conceptually, marked the separation between the lands of Bountiful and Desolation (3 Nephi 3:23; see Alma 22:32). . . . [John L. Sorenson, Images of Ancient America, p. 202]