Question: North Jersey and South Jersey are separated by what river?

Context paragraphs:
South Amboy station: South Amboy is a station on New Jersey Transit's North Jersey Coast Line located in South Amboy, New Jersey, United States.  The station is 2½ miles south of Perth Amboy station and 5 miles northwest of Aberdeen-Matawan station.  Electric trains from the north started terminating here in 1938, and many still do.  This station is located at grade level on Mason Street, and has a high-level island platform serving two tracks.

Conrail Shared Assets Operations: Conrail Shared Assets Operations is the commonly used name for modern-day Conrail (reporting mark CRCX).  Conrail is an American railroad company.  It operates three networks—the North Jersey, South Jersey/Philadelphia, and Detroit Shared Assets Areas, where it serves as a contract local carrier and switching company for its owners, CSX Transportation and the Norfolk Southern Railway.  When most of the former Conrail's track was split between these two railroads, the three shared assets areas (a total of about 1,200 miles of track) were kept separate to avoid giving one railroad an advantage in those areas.  The company operates using its own employees and infrastructure, but owns no equipment outside of MOW equipment.

Red Bank station: Red Bank is a commuter train station located in Red Bank, Monmouth County, New Jersey, United States.  It is one of 20 New Jersey Transit commuter rail stations on the North Jersey Coast Line.  It is located on Bridge Avenue between Monmouth and Oakland Streets, just south of the Navesink River, and consists of two high-level platforms on either side of grade crossings.

Point-No-Point Bridge: Point-No-Point Bridge is a railroad bridge crossing the Passaic River between Newark and Kearny, New Jersey in the New Jersey Meadowlands. The swing bridge is the fourth from the river's mouth at Newark Bay and is 2.6 mi upstream from it.A camelback through truss bridge, it is owned by Conrail as part of its North Jersey Shared Assets and carries the Passaic and Harsimus Line used by CSX Transportation and Norfolk Southern.  River Subdivision (CSX Transportation) accesses the line via Marion Junction.

Perth Amboy and Elizabethport Railroad: The Perth Amboy and Elizabethport Railroad was a railroad operated by the Central Railroad of New Jersey (CNJ).  It was an independent company when it started construction in 1871, but was taken over by the CNJ in 1873.  The railroad diverged from the CNJ main line at Elizabethport and ran to South Amboy, where the New York and Long Branch Railroad (NY&LB) would go on to Bay Head.  South of a junction with the Perth Amboy and Woodbridge Railroad in Perth Amboy, the Pennsylvania Railroad had trackage rights to connect with the jointly-controlled NY&LB; this portion was electrified in 1935.  When the CNJ terminal in Jersey City closed, CNJ trains would run to Newark where passengers transferred to Pennsylvania Railroad or PATH trains to New York City.  Today it is a part of New Jersey Transit's North Jersey Coast Line and Conrail's Chemical Coast Secondary.

Rutgers University–Camden: Rutgers University–Camden is one of three regional campuses of Rutgers University, New Jersey's public research university.  It is located in Camden, New Jersey, United States.  Founded in the 1920s, Rutgers–Camden began as an amalgam of the South Jersey Law School and the College of South Jersey.  It is the southernmost of the three regional campuses of Rutgers—the others being located in New Brunswick and Newark.  The city of Camden is located on the Delaware River, east of Philadelphia.

South Jersey: South Jersey comprises the southern portions of the U.S. state of New Jersey between the lower Delaware River and the Atlantic Ocean.  The designation of southern New Jersey with a distinct toponym is a colloquial one rather than an administrative one, reflecting not only geographical but also perceived cultural differences from the northern part of the state, with no official definition.

North Jersey: North Jersey comprises the northern portions of the U.S. state of New Jersey between the upper Delaware River and the Atlantic Ocean.  The designation of northern New Jersey with a distinct toponym is a colloquial one rather than an administrative one, reflecting not only geographical but also perceived cultural differences from the southern part of the state, with no official definition.

Jersey Shore: The Jersey Shore is the coastal region of the U.S. state of New Jersey.  Geographically, the term encompasses about 141 mi of oceanfront from Perth Amboy in the north to Cape May Point in the south, bordering the Atlantic Ocean.  The Jersey Shore area includes Middlesex, Monmouth, Ocean, Atlantic, and Cape May counties.  While there is no defined border between North Jersey and South Jersey, the Raritan River, Manasquan River or I-195 are often mentioned as the border, with most of the shore region being located in South Jersey.  Many New Jersey residents refer to it simply as "The Shore", as in to go "down the shore", or to have done something "down the shore".

North Jersey Coast Line: The North Jersey Coast Line is a New Jersey Transit commuter rail service between New York Penn Station or Hoboken Terminal and Bay Head, New Jersey.  It is electrified as far south as Long Branch.  On rail system maps it is colored light blue, and its symbol is a sailboat.  It is based on what was once the New York & Long Branch Railroad which was co-owned by the Central of New Jersey and the Pennsylvania Railroad.

Supporting paragraphs: North Jersey South Jersey
Answer: Delaware River