To say the least, it seems most unlikely that a young farm laborer in 1830 would be sufficiently aware of the topography of Jerusalem, much less be able to incorporate it (and dispense with it) so flawlessly into a fictional account.
Some could argue that these texts merely reflect the fact that Joseph Smith knew his Bible well and, consciously or otherwise, imitated its language when it talks about Jerusalem, such as in the well-known parable of the Good Samaritan. While it is true that the Bible was the basis of education in most 19th century households, this would not explain the perfect consistency of the usage of the terms referring to travel to and from Jerusalem in Nephi’s writings and throughout the entire Book of Mormon.
Further mitigating against this idea is an observation by Joseph Smith’s mother. In her history she notes that the young Joseph was actually inclined to read less than his siblings, being more given to “meditation.”2 And there is also the well-known account of how in translating the golden plates, Joseph knew so little about old Jerusalem he was unaware that it had a wall around it. 3
Jerusalem is treated differently in Nephi’s “travel account” from every other mention of it in the Book of Mormon, whether made by him or by later authors.By any measure, these subtle but consistent patterns throughout the entire Book of Mormon signal that The First Book of Nephi was written by someone with first-hand experience with the topography of old Jerusalem.
The most economical explanation thus remains that the author was indeed Nephi, younger son of Lehi and Sariah of Jerusalem.
1. That exception is 2 Nephi 17:1 where Nephi quotes from Isaiah’s text (found in our Isaiah 7:1), that Israel and the king of Syria “went up towards Jerusalem to war against it.”
2. Scot & Maurine Proctor, Joseph Smith’s History
3. Scot & Maurine Proctor, Joseph Smith’s History