Alma 22:31,32 wrote:And they came from there up into the south wilderness. Thus the land on the northward was called Desolation, and the land on the southward was called Bountiful, it being the wilderness which is filled with all manner of wild animals of every kind, a part of which had come from the land northward for food.
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.

You've read that statement made by Alma many times and you think you understand it, but do you? It's a day and a half's journey for a Nephite -- but a journey through what? The land of Desolation is located north of the narrow neck and Bountiful is located south of the neck. That seems simple enough or, does it? Apologists have assumed the day and a half was the distance across the width of the narrow neck from Sea West to Sea East, but is it?
No, it's not the distance of the width of the narrow neck from side to side or east to west! That is not what Joseph Smith implied. It's the distance of the length of the narrow neck from north to south, the neck being between the seas! In other words, it's not a distance measured on a horizontal run from east to west but a vertical run from north to south!
1) "on the line Bountiful"
2) "and the land Desolation,"
3) "from the east"
4) "to the west sea"
5) "a small neck of land"
6) "between the land northward and the land southward"
In other words, the distance is measured from Bountiful's northern horizontal border which is "on the line Bountiful" to the southern horizontal border of Desolation!
From border to border, north and south, leading through the narrow neck that is flanked by the seas!
Psyche!

The "distance" is what it takes for a healthy man to march from the line Bountiful through the narrow neck until reaching Desolation. It's "the journey for a Nephite", one who is healthy and strong, an ordinary man, to make the march in average time. It's not a reference to a marathon or a race but the amount of time it takes an ordinary man to march the distance from point A to point B. That's what Joseph Smith meant regarding the distance of the narrow neck in the above reference.
Hence, the distance is what it takes to traverse the narrow neck from north to south or from south to north across and through the narrow neck. It's the distance from the line Bountiful to the land Desolation!
BUT what about the distance of the narrow neck from side to side, or from east to west -- the actual WIDTH of the neck that separates the two lands? Everyone has wrongly assumed it was a day and a half because they have misinterpreted Joseph Smith's words. But, behold, the Book of Mormon gives us an exact answer to that question and it's not something the apologists take kindly to. Not at all! They obfuscate Smith's words in order to appease their listeners and defend the Church at any cost.
We learn in Helaman 3 that there were mass Nephite migrations from Zarahemla and the southern lands northward of the narrow neck. The northern lands became greatly populated even to a great distance where there were large bodies of water and many rivers. Helaman 4 tells of war between the Nephites and Lamanites; moreover, the campaigns of the Lamanites were so successful "they succeeded in obtaining possession of the land of Zarahemla; yea, and also all the lands, even unto the land which was near the land Bountiful."

This is when we learn that "the Nephites and the armies of Moronihah were driven even into the land of Bountiful" with their backs to the narrow neck they faced the approaching Lamanites to the south who had taken all the lands south. The Nephites had no choice other than to stand their ground and fight or flee into the land northward. The Nephites stood there ground and went down to battle against the Lamanites and in time they regained half the territory.
Now, with that said, prior to the time when the Nephites regained territory from the Lamanites and while their backs were up against the narrow neck and left to defend Bountiful we are given the GOLDEN KEY for the narrow neck of land!
It would have been utterly disastrous if the Lamanites had penetrated the narrow neck and entered the northern lands with the Nephites being held up in Bountiful! That would have been a worse case scenario from a military point of view. The Nephites did not flee northward but elected to stand their ground and fight!

And so, the most important thing they could do at this juncture was to secure the narrow neck and all the passes that lead through it! And therefore, they "fortified and stationed their armies to defend their north country"; thus, they placed their military on a line to defend the narrow neck from all who dare to penetrate! They fortified the line, plugged the holes, and defended the north country!

And in that same verse (Helaman 4:7) we are given the GOLDEN KEY to the narrow neck which tells us exactly how WIDE the neck is on a line from sea to sea:
"a day’s journey for a Nephite"

Or in other words, it takes a Nephite a day to traverse the narrow neck on a horizonal line!
Helaman 4:7 wrote:And there they did fortify against the Lamanites, from the west sea, even unto the east; it being a day’s journey for a Nephite, on the line which they had fortified and stationed their armies to defend their north country.

The Isthmus of Delmarva on the "line" Bountiful from sea west to sea east is a day's journey for a Nephite man!
1 day!
I bear testimony of these things that they are verily true, as Joseph Smith is my witness.
In the name of Joseph Smith,
Amen.