Mill Creek begins in extreme eastern Millcreek Township and travels westward until it is joined by a couple of smaller tributary streams.

From there, it roughly follows Pennsylvania Route 505 (Glenwood Park Avenue) northward until the creek is diverted underground.

One of the bridges is designed to act as a "drift catcher", preventing large debris from entering the tube further downstream.

[8] Mill Creek had a history of overflowing its banks, with one happening in 1893; however the worst such flood occurred on August 3, 1915.

After a series of storms produced over 5.77 inches (147 mm) of rain in 13 hours, saturated soil on the banks collapsed, carrying numerous small outbuildings into the creek.

[12] As the tube is "large enough for a Jeep or [a] pickup to ride through—and turn around in", it is occasionally the site of water rescues when people have been swept into it when the creek is high and have become stranded.

[5] It underwent a $476,800 restoration from May to August 2010 to seal cracks, repair deteriorating concrete and inspect one of the bridge's retaining walls.