New Hampshire, like all other states, must redraw its electoral districts every 10 years, making adjustments based on the population and demographic shifts tabulated in the U.S. Census. Redistricting, in general, has a history of becoming very political, with the party in power redrawing lines in their favor. That is where the term "gerrymandering" comes from.
In addition to districts for U.S. House, districts and wards for the New Hampshire House, Senate, and governor's Executive Council were redrawn by the Legislature in 2012.
There wasn't any disagreement on the congressional districts, but plans for state House districts met more controversy when Democratic Gov. John Lynch vetoed the plan developed by the Republican-lead Legislature, saying it disenfranchised communities that should have received their own House representatives.
The terms of a successful 2006 ballot initiative had required that "when the population of any town or ward, according to the last federal census, is within a reasonable deviation from the ideal population for one or more representative seats, the town or ward shall have its own district of one or more representative seats."
The House and Senate Republican majorities were large enough to override the veto, but opposition didn't stop there. Several groups, including some cities and towns, challenged the House redistricting plan in court for many of the same reasons cited by Lynch in his veto message. The cases were consolidated and fast-tracked to the New Hampshire Supreme Court.
The high court ruled unanimously that the House plan did not violate the constitution.
"The legislature had a choice to make: adhere to the 10 percent rule and give fewer towns, wards and places their own districts or exceed the 10 percent rule and give more towns, wards and places their own districts. This is a policy decision reserved to the Legislature," the Justices wrote.
In 2019, the Legislature passed a bill that would have put the power to draw New Hampshire's voting districts in the hands of a 15-member independent commission. Gov. Chris Sununu vetoed that bill.