The densely settled center of town, where 5,797 people resided at the 2020 census,[5] is defined as the Newmarket census-designated place and is located at the junction of New Hampshire routes 108 and 152, along the Lamprey River.

Incorporated in 1727, Newmarket is one of six towns granted by Massachusetts in the last year of the reign of King George I.

The return cargo brought whale oil, molasses and rum back to Newmarket.

[10] The company had cotton shipped up from the Deep South, so its production was adversely affected by the Civil War.

The company built dams far upriver to create Pawtuckaway Pond in Nottingham and Mendums Pond in Barrington—during drought, the company could release a regulated flow of water from the dams into the Lamprey to run the works.

[10] Newmarket was affected by the 1922 New England Textile Strike, shutting down mills in the town over an attempted wage cut and hours increase.

In the 1970s, the mill served as the headquarters of the Timberland Company, during the years when it grew from a small work-boot manufacturer to a leading "urban" fashion brand.

[18] Buddhist practitioners among the Laotians attend the Wat Lao Mixarayam Temple in Lowell, Massachusetts.

[20] Newmarket Fire and Rescue also provides the neighboring town of Newfields with an ambulance transport service.

In 2017, staff were awarded a Unit Citation by the New Hampshire Division of Fire Standards and Training and Emergency Medical Services for heroic actions undertaken at a car accident in 2017.

[21] The town is also the site of several publicly available electric vehicle charging stations, including at the Newmarket Library and Schanda Park.