Verse 16 is repeated to give the context for the "mother Gentiles" mentioned in verse 17. While the early vision concentrated on Nephi's descendants, the redemptive section of the vision shifts contexts to the events of the North American continent, and the story of the founding of the United States. Very clearly there is a large amount of the history of the New World which is being summarily dismissed from the vision. The reason is that the vision is concentrating on the crucial events which tell the essential story, that is the fall and redemption of Nephi's seed. The events of the creation of the United States, the location and atmosphere into which Joseph Smith is born, are critical to that redemptive process.