Permits will be available online or at the district's general headquarters in River Forest.
Nearly 10 percent of the total picnic permits sold for the year are sold on the first day.
You can buy your permits here: https://picnic.fpdcc.com/
Permits must be obtained for groups of 25 or more. Two picnic permits per person or organization are allowed each year. Permits for groups larger than 399 people have to be purchased in person.
In-person sales take place from 8 a.m. to 4 p.m. at the headquarters of the Forest Preserve District of Cook County, which is located in River Forest.
The Forest Preserve District sold 8,122 permits in 2011 and a big chunk of them -- about 1,044 or 13 percent -- were issued the first day.
Last year, county officials say one million people participated in permitted picnics held at forest preserve districts.
The Associated Press contributed to this report.