There are 10 different states in the U.S., including Texas, that use the color purple as a warning to trespassers.
Purple shows well in the outdoors. In fact, it's one of the only colors that colorblind people can easily identify. Having said that, just seeing it on a fence post or painted on a tree as you go by might only garner a quick glance and an odd look.
As Jonathan Kennedy of EastTexasLands.com says in the video, "The reason they did that is they were trying to keep landowners from constantly having to replace signs."
Originally landowners were required to have a "no trespassing" or other sign posted to explain the purple paint, but only one year later that rule was rescinded. The law states that the paint must be marked in vertical lines a minimum of 8 inches long and at least 1 inch wide.
The marked posts or even trees must have clearly visible paint and that paint must be placed 3-5feet from the ground. Other states with purple paint rules include Kansas, Arizona, Montana, Arkansas, Idaho, Florida, Maine, North Carolina, Missouri and Illinois.
No matter what state you're in, "posted" and other no-trespassing signs can be a headache for landowners to constantly replace.
Now we just need more states to get in on the purple paint rule. The only thing left to be done is to share the meaning of the rule so everyone knows!