The ghosts like the rain. Whether it's the water or the cast of the sky, something about wet weather makes the faded signs seem more vivid. You see details of an ad that's been pitching flour since Woodrow Wilson was president, a sign for a store that was a memory when 35W carved up the neighborhood.
By contrast, the new billboards wipe themselves clean every few seconds, swapping one bright ad for another. Pull the plug and they're dark; reprogram the chip and a new set of pictures blares bright. The old billboards were made to last longer, and they did.
A century of wind and rain hasn't erased them. A hundred years of sunshine couldn't fade them completely. All that strength and endurance — and they could be gone in an afternoon if someone got industrious with a brush.
There are several kinds of ghost signs.
• The Eternal. Intact, brilliant, crisp, hardly ghostly at all. In other words, fake. Or restored. Sometimes a building owner or a city will decide that the signs lend atmosphere to the street, provide a reminder that this isn't a strip-mall where "history" means "Radio Shack was in that spot until last month." It's nice, and better than erasing them, but they lose something when they're brought back to life. It's a bit like watching Gloria Swanson smile in "Sunset Boulevard."
• The Rip Van Winkle. Often the destruction of an old building reveals a sign on the adjacent property's wall, and you wonder if the guy who paid for it got anything to compensate for the sign's obliteration. These signs can be startling. They blare out a brand long gone with the same bright cheer, even if it's been unseen for 50 years. A local example would be the Gethsemane Episcopal Church sign on 4th Avenue S. and 10th Street in downtown Minneapolis. It was covered by the Leamington Motor Lodge, and when that battered flophouse was knocked down in 2008, the pristine church sign was revealed again.
Sometimes these signs are doomed by a new building. At the shopping center across Nicollet from Richfield's Hub, a renovation stripped away some cheap spray-on spackle and released a perfect Warner Hardware sign. It lasted longer than the old Warner ghost on Hennepin Avenue S. and 5th Street, which advertised all the locations of Warner stores, but it, too, was obscured again. It's not like Warner was paying the owner any money, you know.
• The Palimpsest. So named for ancient documents that have been erased and written over. The palimpsest ends up looking like abstract art, with pictures and words overlaid on words and pictures, Coke over coffee, coffee over tobacco.