This abandoned railway line was built in the late 1800s to connect the Reading Railroad's mainline at Wilmington with various industries near Brandywine Creek. (A bridge on the route shows a date of 1883.) These industries included the "DuPont Experimental Station", a black powder plant at Hagley and some textile mills. The line also served various passenger stops along the way, with the last one on the line being Kentmere Station, east of Rockford Park.
The line was actually composed of two small spurs; one that went northeastwards to the textile mills and the experimental station, the other went east and southeast to Kentmere Station. The lines branched shortly after passing under DE Route 52. No physical evidence of the spur to the mills remains, and it is not marked on topographical maps.
The entire line (including both spurs) was abandoned in the 1950s. Evidence of the former line still exists: a tunnel on the route (Delaware's only railroad tunnel), a bridge over Rising Sun Lane, and tree-lined clearings are all that is left.
See also the Brandywine Industrial Track.
Thanks to Joe Sharretts for contributing information about this route.