The Christiana Branch started out in 1849 when the Pusey & Jones Shipyard Co. was founded in Wilmington, DE and immediately needed a way to get freight and workers to the yards fast. Cars would not be around for about 60 more years so it was slow to get from Baltimore and Philadelphia to Wilmington. The PB&W built the line and opened the same year as the yard opened and connected to the Northeast Corridor. The line was extremely successful and brought more than 75% of the company's profits. In the 1860s and the 1870s the PRR and the RRR connected their NCC Cutoff and Millside Line to the area now known as Christiana Junction. The wild success of the line gained the interest of the PRR and they quickly bought out the company.
The PRR would make astonishing upgrades to the line and would make big money up until the 1950s after the war ended. The need for small war vessels and yachts was no longer needed and the company went out of business. The PRR did not abandon the line and bought the Millside Line to keep a profit. Serving small industries such as railroad car builders and goods manufacturers, the line could not turn a profit and in the summer of 1976 the line was abandoned.
Today the line still is in place at Christiana Junction but dead ends at the first crossing. The rails were not torn up by the PRR but instead were paved over when a new baseball stadium was built and the Riverfront project was put in place.
Thanks to Christian B. for contributing information about this route.