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Illinois Posting Laws: How to Post Land
Illinois gives landowners two ways to post: a sign, or purple paint on trees or posts. Since 2013 the old rule to also put up a sign alongside paint is no longer in effect. The statute sets no sign size or spacing in the statute text we read. This guide explains how the paint option works.
What the law asks for on signs
The Illinois trespass law, 720 ILCS 5/21-3, sets no letter height, sign size, spacing number or owner-name rule in the statute text we read. Signs are the plain, familiar way to give notice. The official ILGA pages blocked our requests, so we relied on the state IDNR page on Public Act 97-0477 and secondary summaries.
Purple paint
Under subsection (b-5), paint on trees or posts around the area is an alternative to signs. The first option is a vertical line at least 8 in long, with the bottom of the mark 3 to 5 ft high, and marks no more than 100 ft apart.
The second option is a post capped or marked on at least its top 2 in, with the bottom of the cap or mark 3 ft to 5 ft 6 in high, and posts no more than 36 ft apart. Either way, marks must be readily visible to any person approaching. The old requirement to also post a sign is inoperative on and after 1 January 2013.
Where paint does not apply
The paint option does not apply in a municipality of over 2,000,000 inhabitants, which means Chicago. If your land is inside that city, plan on signs and read subsection (b-15) closely.
Practical tips
The 100 ft method needs fewer marks along a long edge, while the post method needs a post every 36 ft at most. Walk the line each year and repaint tops that wear off. Keep dated photos of your marks and any signs.
Questions about posting land in Illinois
Is purple paint allowed for posting land in Illinois?
Yes. Under 720 ILCS 5/21-3(b-5), purple paint on trees or posts is an alternative to signs. One option is a vertical line at least 8 in long, bottom of the mark 3 to 5 ft high, and no more than 100 ft apart.
Do I still need a sign with purple paint in Illinois?
No. The old requirement to also post a sign, in subsection (b-10), is inoperative on and after 1 January 2013. Paint marks must still be readily visible to any person approaching. Read the current statute to confirm.
Does the Illinois paint rule apply in Chicago?
No. Subsection (b-15) says the paint option does not apply in a municipality of over 2,000,000 inhabitants, which is Chicago. We could not read the current statute text directly on ILGA, so verify it yourself.
This guide explains the law in plain words; it is not legal advice. We read the statute text on 2026-10-24. Laws change: check the current text here or ask your county or state wildlife agency.