Minecraft wiki entry for Historical_effects, associated text: Beyond 16,777,216 blocks, precision loss exceeds one full block, and redstone renders even more oddly as a result. For example, only half (if exceeded on one axis) / a quarter (both axes) of all redstone dust placed here will actually render - the rest, while it still exists, functions and influences the visual connections of redstone that does render, will remain entirely invisible. Of what does render, redstone will be stretched to visually occupy two blocks if over this distance on one axis, or a 2x2 space of blocks if beyond it on two.