In 3 Nephi 6:8 we read:
And there were many highways cast up, and many roads made, which led from city to city, and from land to land, and from place to place.
This fits what we know about Mesoamerican highways which were “cast up”. Mark Wright explains:
Although they varied in height and width, their construction was generally composed of rubble lined with large stones at the edges and large cobblestones in the interior, progressively getting smaller from bottom to top, finally gradating to fine gravel near the surface and topped with fine powdered limestone (called sascab), which was pressed smooth with stone rollers– Mark Alan Wright, “The Cultural Tapestry of Mesoamerica,” Journal of the Book of Mormon and Other Restoration Scripture 22, no. 2 (2013): 14.
How would Joseph Smith have remembered small details like this when dictating?