[4] The area that today is Rockingham County was first settled by Europeans moving north from the Plymouth Colony in Massachusetts as early as 1623.

The government was linked tightly with Massachusetts until New Hampshire became a separate colony in 1679, but counties were not introduced until 1769.

It is named for Charles Watson-Wentworth, 2nd Marquess of Rockingham, who had been Prime Minister of the UK from 1765 to 1766.

In 1997, the county court facilities were moved to Brentwood, a rural town adjacent to Exeter.

[13] In terms of ancestry, 26.9% were Irish, 19.0% were English, 14.8% were Italian, 9.7% were German, 7.3% were French Canadian, 5.6% were Polish, and 3.8% were American.

Three Democratic presidential nominees have won it since 1964, including Joe Biden in 2020, who was the first to win a majority since Lyndon B. Johnson.

After redistricting based on the 2010 United States census, Rockingham County was split between 8 state senate districts:[20] Strawbery Banke Museum in Portsmouth is a collection of historic buildings from the 17th through 19th centuries.

Rockingham Park racetrack, which featured weekly horse racing until 2009, was also in Salem.

The site of the former track, next to the Mall at Rockingham Park, is being redeveloped as Tuscan Village, a mixed-use development.

America's Stonehenge, which claims to be a pre-Columbian collection of stone structures, is in northern Salem.

Derry was home to poet Robert Frost, who taught at nearby Pinkerton Academy.

Rockingham County is also home to New Hampshire's entire seacoast and features several popular resort towns.

Rye features several undeveloped beaches such as Odiorne Point State Park and contains New Hampshire's portion of the Isles of Shoals.

Towns in Rockingham County that send their public high school students to Pinkerton, other than Derry, include Auburn, Candia, Chester, and Hampstead.