Some 200 members of Teamsters Local 700 are off the job.
Contract negotiations continue.
"All the employees of the Forest Preserves are critical to our success, and that certainly is the case for the members of Local 700. We recognize and appreciate the work they do every day all year long to keep the Preserves a place that is a gem in Cook County. Working within our current and long-term fiscal restrictions, the Forest Preserves has made offers to the union that continue to provide a compensation package that is at and above what is competitive in the labor market. We are confident that we can negotiate with the union to find a solution within our confines," said General Superintendent Adam Bianchi.
All forest preserves will remain open during the strike.