Purple paint on a fence post indicates that you are in danger and should leave the area immediately.
On 18 August 2015, the Jacksonville, Texas, television station KETK aired a segment that retriggered interest about a state law that many Texas residents were apparently unfamiliar with, one holding that markings of purple paint carry the same legal significance as “No Trespassing” signs:
While visiting the countryside of Texas, have you ever seen trees and fence posts with unique markings the color purple? It’s not backwoods graffiti, it means no trespassing.
“It holds the same weight and the same law violations apply,” said Prairie View A&M Extension Agent Ashley Pellerin. “It’s no trespassing period.”
Enacted in 1997, the law states that the application of purple paint (typically in a shade known as “No Hunting Purple”) to property features such as trees and fence posts in a specified manner is the legal equivalent of posting “No Tresspassing” signs:
“Notice” means: an oral or written communication by the owner or someone with apparent authority to act for the owner; or fencing or other enclosure obviously designed to exclude intruders or to contain livestock; or a sign or signs posted on the property reasonably likely to come to the attention of intruders, indicating that entry is forbidden; or the placement of identifying purple paint marks on trees or posts on the property. If purple paint is used, then the purple paint must be vertical lines of not less than eight inches in length and not less than one inch in width; placed so that the bottom of the mark is not less than three feet from the ground or more than five feet from the ground; and placed at locations that are readily visible to any person approaching the property and no more than: 100 feet apart on forest land or 1,000 feet apart on land other than forest land.
That law spares landowners, particularly in rural areas, from having to continually replace printed signs that often end up being stolen or eradicated by the elements.
Although purple paint can be used in place of “No Trespassing” signs in the state of Texas (if its application meets the requirements listed above), this information has been circulated online under misleading clickbait titles such as “If You See Purple Paint on a Fence Post, Pay Attention! It Could Save Your Life,” leaving readers with the mistaken impression that such markings indicate imminent danger.
Although a person who willfully enters an area marked with “No Trespassing” warnings (either in the form of signs or paint) might be subject to criminal or civil penalties, such warnings do not in themselves indicate any significant level of danger, much less an imminent threat to life. In general, landowners may not use deadly force to protect property; they may only employ reasonable measures to repel trespassers (unless they believe those intruders pose a threat of great bodily harm or death).
Only a few states, including Illinois, Missouri, North Carolina, and Texas, have so far enacted formal laws establishing purple paint markings as the legal equivalent of “No Trespassing” signs.