AbstractData on polycyclic aromatic hydrocarbons (PAHs) measured in surface sediment and cores in the New York/New Jersey Harbour under the Contamination Assessment and Reduction Project (CARP) was examined via Positive Matrix Factorization (PMF), which revealed six sources. Two represented the higher and lower molecular weight (MW) fractions of coal tar and/or creosote (pyrogenic) sources and explained 49% of PAH mass in the sediment samples. Two sources were related to uncombusted petroleum (petrogenic) sources, such as heavy fuel oil and crude oil, and explained 30% of PAH mass. The final two sources were related to combustion (pyrogenic) sources such as gasoline‐ and diesel‐fuelled vehicles and explained 21% of the PAH mass. Sediment cores revealed that Σ22PAH increased from the pre‐industrial period until about 1980 and then decreased because of efforts to control water pollution via mechanisms such as the Clean Water Act.