How far behind the Ark were the people supposed to be?
The people were to keep a space of about 2,000 cubits between themselves and the Ark. That distance is roughly 3,000 feet, or a little over half a mile. They were not to come near it, so they could know the way they must go.
Les explains that the Ark of the Covenant, the gold-overlaid box containing the tables of the Ten Commandments, a sampling of the manna, and Aaron's rod that budded, with the mercy seat above it, signified the very presence and mercy of God and would lead the children of Israel. In verse 4 the command specifies a space of about 2,000 cubits—about 3,000 feet, a little over half a mile—between the people and the Ark. Les notes they were never to get too close, so that by following at that distance they might know the way they must go, for they had not passed that way before.
Yet there shall be a space between you and it, about two thousand cubits by measure: come not near unto it, that ye may know the way by which ye must go: for ye have not passed this way heretofore.