AUGUSTA — All 48 state parks and historic sites will celebrate Maine Residents Day this Sunday, June 16, by offering Maine residents free admission.

All vehicles bearing Maine license plates will be allowed free entrance to state parks and historic sites on that day, which is also Father’s Day. No rain date will be available.

The open admission does not apply to the Penobscot Narrows Observatory in Prospect, though admission to Fort Knox State Historic Site will be free that day. A number of the parks will be hold special events that day.

Last year, more than 2.6 million people visited Maine state parks and historic sites for day use and camping, the largest number of visitors in the past 21 years, according to Bureau of Public Lands figures. Many of the parks and historic sites were able to open early because of the unusually warm, clear weather, with some parks opening five weeks earlier than usual.

For more information about the events on Sunday, as well as general information on Maine state parks and historic sites, go to: www.parksandlands.com.