Have state borders changed since this sign was made?

Author here. Rock City has been painting "See Seven States" on barn roofs across the South since the 1930s, and the marker at the top of Lookout Mountain names all seven. We tested it with thousands of sightlines through 30 m terrain data: a full 360 sweep from the marker, point to point runs to every landmark the marker names, and viewsheds from 20 points along both brows of the mountain, cranking atmospheric refraction well past anything a real atmosphere produces.

From the marker itself you get three states (Georgia, Tennessee and a sliver of North Carolina). Walk over to the west brow and Alabama shows up, about 21 km out. South Carolina, Kentucky and Virginia stay behind terrain from every point on the mountain no matter what refraction we assumed. Copernicus GLO-30 is a surface model, so tree canopy is already baked into the terrain. It doesn't change the verdicts, the three missing states sit behind ridges by 1.4 to 2.8 km and no forest is that tall.

To be clear, nothing against Rock City. The barns are a piece of Americana and the view really is spectacular, it just has three states in it, maybe four. This started as a fun curiosity and got a bit out of hand.