There is a U.S. assayer's office here, and there are extensive shipyards, a large paper mill, iron works, and, just outside the city limits, the smelters of the American Smelters Securities Company, in connexion with which is one of the two plants in the United States for saving arsenic from smelter fumes.
Perth Amboy has a good harbour, shipyards and dry-docks.
For many years there were important cod and mackerel fisheries here and Duxbury clams were famous; there were large shipyards in Duxbury in the 18th century and in the first half of the 19th.
The tall columnar trunk furnishes the most valued pine timber of the states; close-grained and resinous, it is very durable and polishes well; it is largely employed in American shipyards, and immense quantities are exported, especially to Britain and the West Indies.
After 1890 important shipyards were established near San Francisco.