The Trenton Subdivision is a railroad line owned by CSX Transportation in the U.S. states of Pennsylvania and New Jersey.

The line runs from CP NICE in Philadelphia, Pennsylvania, northeast to Port Reading Junction in Manville, New Jersey.

The north end of the Trenton Subdivision at Port Reading Junction is where the Conrail Lehigh Line (in the North Jersey Shared Assets Area) heads northeast and the Norfolk Southern Railway Lehigh Line heads west.

The former southernmost piece of the Trenton Subdivision, from its south end across the Columbia Railroad Bridge to Belmont, opened in 1834 as part of the Main Line of Public Works.

[5] The Philadelphia and Reading Rail Road opened in 1839, including from Belmont north to the junction with the Norfolk Southern Railway's Harrisburg Line near the Falls of the Schuylkill.