Naylors Run is a 4.6 miles (7.4 km) tributary

Tributary

A tributary or affluent is a stream or river that flows into a main stem river or a lake. A tributary does not flow directly into a sea or ocean...

 of Cobbs Creek

Cobbs Creek

Cobbs Creek is an tributary of Darby Creek in Delaware County, Pennsylvania in the United States. It forms an approximate border between Montgomery County and Delaware County. After Cobbs Creek passes underneath Township Line Road , it forms the border between Philadelphia County and Delaware County...

 in Havertown

Havertown, Pennsylvania

Havertown is a residential suburban unincorporated community in Haverford Township, Delaware County, Pennsylvania, United States, approximately 9 miles west of the center of Philadelphia. Havertown's ZIP Code is 19083. Havertown is notable for being the birthplace of Swell Bubble Gum, which closed...

 and Upper Darby

Upper Darby Township, Pennsylvania

Upper Darby Township is a home rule township bordering West Philadelphia in Pennsylvania. Although it retains the term "Township" in its legal name, presumably for historic reasons, it is the largest municipality of any type in Delaware County. Upper Darby is also home to the Tower Theater, a...

, Pennsylvania

Pennsylvania

The Commonwealth of Pennsylvania is a U.S. state that is located in the Northeastern and Mid-Atlantic regions of the United States. The state borders Delaware and Maryland to the south, West Virginia to the southwest, Ohio to the west, New York and Ontario, Canada, to the north, and New Jersey to...

 in the United States

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

.

Naylors Run flows underground in Upper Darby from Sherbrook Boulevard to Walnut Park Drive, where it joins Cobbs Creek. Thousands of feet of Naylor's Run were channeled into underground culverts to facilitate commercial and residential development in the filled land above the pipes. Along its banks was the early-1900s Babies Hospital and the National Wood Preservers, which dumped hazardous material into the creek. Naylors Run joins Cobbs Creek near City Line Avenue.