Port Glasgow is the second largest town in the Inverclyde council area of Scotland. The population according to the 1991 census for Port Glasgow was 19,426 persons and in the 2001 census was 16,617 persons. It is located immediately to the east of Greenock and was previously a burgh in the former county of Renfrew.
The town was originally named Newark but due to ships not being able to make it all the way up the shallow river Clyde it was formed as a port for nearby Glasgow in 1668 and became Port Glasgow in 1775. Port Glasgow was home to dry docks and shipbuilding beginning in 1762.
The town grew from the central area of the present town and thus many of the town's historic buildings are found here. Port Glasgow expanded up the steep hills inland to open fields where areas such as Park Farm, Boglestone, Slaemuir and Devol were founded. This area has subsequently become known as upper Port Glasgow and most of the town's population occupies these areas.
The origins of Port Glasgow go back to the construction by Sir George Maxwell between 1450 and 1477 of the "New Werke of Finlastoun", which became Newark Castle. At a good anchorage near the castle, a small fishing hamlet known as Newark formed, like other scattered hamlets along the shores of the River Clyde. After 1589 the village of Greenock formed just under to the west of Newark, and gradually became a market town with growing fishing and sea trade, although it had only a jetty in the bay to unload ships. Since seagoing ships could not go further up the Clyde due to sandbanks, the Glasgow merchants such as the Tobacco Lords wanted harbour access, but got into arguments with Greenock over harbour dues and warehouses. They put a bid in for the Easter Greenock estate for a harbour, but were outbid and the lands became the Barony of Cartsburn. They then negotiated with Sir Patrick Maxwell of Newark Estate, and in 1668 he agreed to lease the City of Glasgow of land to the west of the castle, for payment of 1,300 merks and an annual feu duty of four merks. Construction of piers and breakwaters enclosing the harbour began promptly, and Newport Glasgow was constituted as a free port.
Trade prospered quickly, and by 1710 Newport Glasgow had the principal Clyde custom house, initially in Customhouse Lane, then after 1754 in a new building constructed on the west quay of the harbour. Through that century the town became known simply as Port Glasgow. Ships, mostly owned by Glasgow merchant ships, imported tobacco, sugar, rum, cotton and mahogany from the Americas, as well as timber, iron and hemp from the Baltic. These goods were then taken by road to Glasgow, as was market garden produce from farms around Port Glasgow. A change began in 1773 when the Lang Dyke was constructed to deepen the upper river, and ships increasingly went upriver straight to Glasgow. In 1830 the custom house collected £243,349 3s 1d in revenue, but after that income from the port declined, while Greenock has by then its own custom house.
After 1693, the grid-iron street layout which still forms much of the town centre today, was laid out.
In 1780 Thomas McGill set up one of the first shipyards in the area, located near to Newark castle. By the 19th century, Port Glasgow had become a centre of shipbuilding. The Comet was built in the town in 1812 and was the first commercial steam vessel in Europe. A replica of the Comet and a plaque commemorating the actual site of construction are situated in Port Glasgow town centre.