Seeing and sky transparency are very good on average. Varies with each of the two sites. Located in one of the least populated areas of the state. Two small light domes from Carmi and McLeansboro are in the East and West, respectively. The park does have a few pole-mounted lights, but they are in the process of being shielded.
None are visible from the observing areas.
When the leaves are off the trees, you might see one in the distance from either site. Camping is not permitted at the observing sites and signage says that the park closes at 11 p.m., but if you let them know that you are coming, staying all night will not be a problem. The park staff are friendly to astronomers. And please don't litter. We value our relations with the park.