Needles & Grooves

As long as they're evenly packed and so thr weight dispersion doesn't crush any particular side or corner, you should be good.

I did not stack them before leaving my last house, nor upon arrival. However, they were stacked in the moving truck by the movers (on a NV to TX move with a stop at a storage warehouse - so changing trucks). I moved about 1200 records and there was no damage. Some of the boxes were a bit caved in on the edges, but no record damage. YMMV.

Thanks guys.

Stacking is totally fine as long as they're full! Those small size U Haul boxes are just a lifesaver for moving LPs. Do they make a heavy duty version now?

Yup

1/2 my records are in these boxes in my dad’s basement, and he keeps stacking shit on ‘em, so I think/hope it’s all good

I had my records stacked 3 high for about a week or 2 before I moved. They all turned out fine. And those weren't even the heavy duty kind.