This second grant had been set aside to provide fuel and home sites for imported workers at the Lamprey River Iron Works, chartered in 1719 by the Massachusetts General Court to encourage industrial development in the province.

Slow at first to be settled because of rocky soil, Barrington by 1810 had 3,564 residents, then the state's third largest town, its primary industry the smelting of iron ore.

The Isinglass River, together with its tributaries, provided water power for grist, fulling and saw mills.

In 1820, Strafford was set off from Barrington, reducing its land area by about half, because of lengthy travel required to attend town meetings.

In 1882, the Reverend Alonzo Hall Quint wrote: Indeed, the town's attractive natural features, including rivers, brooks, waterfalls and not less than 14 ponds, are summarized by the name of a 374-foot (114 m) summit, Beauty Hill.

Barrington is bisected by the Calef Highway (New Hampshire Route 125), named for a state senator from the 1800s whose family also founded in 1869 a locally famous general store that remains in operation.

The highest point in town is an unnamed summit near its western border, measuring 610 feet (190 m) above sea level.