Amesbury is a city in Essex County, Massachusetts, United States, located on the left bank of the Merrimack River near its mouth, upstream from Salisbury and across the river from Newburyport and West Newbury. The population was 17,366 at the 2020 United States Census. A former farming and mill town, Amesbury is today largely residential. It is one of the two northernmost towns in Massachusetts (the other being neighboring Salisbury).

In 1637, the first English settler in the Salisbury-Amesbury region, John Bayly, crossed the Merrimack River from the new settlement at Newbury, built a log cabin, and began to clear the land for cultivation. He intended to send for his wife and children in England, but they never joined him. He and his hired man, William Schooler, were arrested for a murder Schooler had committed. Schooler was hanged for the murder but Bayly was acquitted. Given the fishing rights on the river by the subsequent settlement, provided he would sell only to it, he abandoned agriculture for fishing.

On September 6, 1638, the General Court of Massachusetts created a plantation on behalf of several petitioners from Newbury, on the left bank of the Merrimack, as far north as Hampton, to be called Merrimac. They were given permission to associate together as a township. The area remained in possession of the tribes along the Merrimack, who hunted and fished there.

The settlers of the plantation, who entered Massachusetts Bay Colony, were rebels in a cause that was settled by the English Civil War (1642–1651). Although nominally subjects of the crown, they did not obey it. The settlers maintained close ties with the Parliamentary cause in Britain. The supreme government of the colony was the General Court, which functioned autonomously, passing its own laws, establishing courts, incorporating townships and providing for the overall defense of the colony. They established a Puritan church rather than the Church of England.

In the early spring of 1639, approximately 60 planters took up residence on land cleared by the natives. In May, an elected planning committee laid out the green, the initial streets, the burial ground, and the first division into lots, apportioning the size of a lot to the wealth of the settler. In November, the General Court appointed a government of six, which required that every lot owner take up residence on his lot. They began to assign lots west of the Pow-wow river. The town was originally named Colchester, but was renamed Salisbury in October 1640, potentially at the suggestion of Christopher Batt, from Salisbury, England. Batt trained the militia in the town. The incorporation of the town granted it legal recognition by the colony to a township of that name, with its own government, empowered by citizens populating a territory of legally defined boundaries. The original Salisbury was many times larger than the present. From it several townships were later separated.

On January 12, 1641, a town meeting ordered the first roads north and west of the Pow-wow River to be built. On April 21, another meeting granted William Osgood 50 acres of “upland” and 10 of “meadow” along the Pow-wow River, provided he build a sawmill for the town to use. It utilized a water wheel driven by the Pow-wow River. The mill produced lumber for local use and pipe-staves for export. A gristmill was added to the Pow-wow river location in 1642. The Powwow River provided water power for a subsequent mill complex. In 1642, the town wanted families to take up residence west of the Pow-wow and form a “New Town.” No volunteers responded.

In 1643, the General Court divided Massachusetts Bay Colony into four counties: Essex, Norfolk, Middlesex and Suffolk. Norfolk contained Salisbury, Hampton, Haverhill, Exeter, Dover, and Strawberry Bank (Portsmouth). This division was a legal convenience based on the distribution of courts. Since the first establishment of four courts on March 3, 1635, the General Court had found it necessary to multiply and distribute courts, so that the magistrates would not spend time in travel that they needed for settling case loads. The main requirement for membership in a shire was incorporation.