The Nine Mile Run Trail at Frick Park in Pittsburgh, PA, is an easy 3.6 mile out-and-back hike that leads from Duck Hollow up Nine Mile Run and over to the eastern side of the park.

Parking can be found in Duck Hollow at the Duck Hollow Trail Parking area. This parking lot serves Frick Park, the Three Rivers Heritage Trail, the Steel Valley Heritage Trail, and the Duck Hollow Trail.

History: In 1922, the Duquesne Slag Company bought land along Nine Mile Run and dumped slag into the valley for 50 years via a railroad track above the creek. About 200 million tons were dumped alongside the banks, which reached ten stories deep.

Starting in 2006, with the help of the US Army Corps of Engineers and the Nine Mile Run Watershed Association, the restoration of Nine Mile Run began and continues to this day. It's the largest restoration of its kind in an urban area in the country.

Nine Mile Run's wetlands naturally filter runoff and the surrounding trees are as vibrant as anywhere else in the city. Walking along Nine Mile Run, without previously knowing its history, you'd have no idea the area used to be a slag dump. You can hike the Nine Mile Run Trail all the way to where the run meets the Monongahela River and the trailhead for the Duck Hollow Trail.