This track was put in place in about 1882, and started in Landlith, DE, switching off the main PRR line there. There was about a mile of street track at that point, after which it broke off from the streets and went through Brandywine State Park, finally ending at some local mills at Augustine Cut-off in Wilmington, DE, at 3.14 miles total length. It was used until Conrail abandoned the line in the late 1970s or early 1980s.
Most of the street track was simply paved over. The section in Brandywine State Park is still intact except for grade crossings and about 1/4 mile of track that was removed for a hiking trail.
See also the The Kentmere Branch.
Thanks to Joe Sharretts for contributing information about this route.