A purple stripe on a tree can legally mean ‘No Trespassing’ in 22 states; in Pennsylvania, the mark must be 8 inches long and 3 to 5 feet above ground

A hike in the rural countryside of Pennsylvania or Texas can take a surprising turn. A tree marked with a thick purple stripe might look like a stray bit of graffiti at first glance, but in a number of states, that mark carries the same legal weight as a printed sign. According to the Pennsylvania Game Commission, the state's official resource management agency, a vertical purple stripe painted on the trunk of a tree or on a post, at least 8 inches in length, 1 inch in width, and 3 to 5 feet above the ground, is equivalent to a "NO TRESPASSING" sign. Because many hiking trails cross both private and public land, it is worth knowing what the color code means before setting out.

Why paint stripes on trees, anyway?

It's all about low-maintenance durability, as per the Pennsylvania Game Commission. Signs can blow over in the wind or get washed away by rain, or even be deliberately removed by hikers who think they're some kind of vandal-proof nuisance. Paint is cheap and lasts a long time. Many landowners have large tracts of land to post. Plus, purple is a color not likely to be used by utility companies or timber companies when marking trees for removal, and it's easier on the eyes for people with red-green color blindness: a rationale that applies specifically to states using purple, not to every color a state has adopted.


It's more widespread than you'd think, but not universal

According to a 2026 legislative briefing prepared for the Vermont Senate Natural Resources Committee, at least 22 states, including Texas, Florida, Illinois, Missouri, Tennessee, and Pennsylvania, have laws of this kind on the books. Counts vary by source and by how strictly "purple paint law" is defined; a separate 2026 industry survey puts the figure as high as 26 when broader posting statutes are included. Not every state uses purple itself: Maryland requires blue, while Arizona, Idaho, and Montana require orange. Orange can be harder than purple for some forms of red-green color blindness to distinguish from autumn foliage, which is part of why color choice differs by state rather than following one universal accessibility standard.

In some states, the markings only apply to hunting, fishing, and trapping, while in others, it's all activities, meaning a hiker or birdwatcher would be subject to the same penalties as a hunter. The University of North Carolina School of Government blog on Criminal Law, which investigated the issue in 2018, notes how courts interpret these statutes, citing Hefley v. State, 2013 WL 5576360 (Tex. App.—Tyler 2013), in which a Texas appellate court upheld a trespassing conviction based in part on purple paint markings along a fence line, establishing that not knowing what the color meant is not a valid defense.

The part you ought to know about

Ignorance of the law is not a valid defense here. Hiking apps such as AllTrails do not always reflect private boundary lines, so relying on them alone is not a guarantee of staying on public land. Even unintentionally getting onto privately owned property marked by purple lines, even during a trail run while wearing your headphones, still counts as trespassing, which means that you can get charged with a fine or misdemeanor, depending on the state.

A generation of outdoor enthusiasts raised on the idea of nearly limitless public land may find these boundaries an unexpected constraint. In practice, the limits of rural property are marked more concretely and more colorfully than many hikers realize. A purple line on a tree is a signal to turn back.