McConnells Mill State Park is on Slippery Rock Creek in Lawrence County, Pennsylvania.

Built in 1852, Daniel Kennedy's gristmill on Slippery Rock Creek was destroyed by fire
so he rebuilt it in 1868. In 1875, Thomas McConnell bought the mill and improved it by
replacing the waterwheel with water turbines and the grinding stones with rolling mills.
One of the first rolling mills in the country, it processed corn, oats, wheat and buckwheat
for local customers.

In 1942, the mill and surrounding property was conveyed to the Western Pennsylvania
Conservancy and later to the Commonwealth of Pennsylvania with the wish that it be preserved
for future generations. McConnells Mill State Park was formally dedicated in October of 1957.