The White Mountains range in New Hampshire spans the north-central portion of the state, with Mount Washington being the tallest in the northeastern U.S., and other mountains like Mount Madison and Mount Adams surrounding it. With hurricane-force winds every third day on the average, over 100 recorded deaths among visitors, and conspicuous krummholz (dwarf, matted trees much like a carpet of bonsai trees), the upper reaches of Mount Washington claim the title of having the "worst weather on earth." A non-profit observatory is located on the peak for the purposes of observing the harsh environmental conditions.

In the flatter southwest corner of New Hampshire, another feature, the prominent landmark and tourist attraction of Mount Monadnock, has given its name to a general class of earth-forms—a monadnock signifying, in geomorphology, any isolated resistant peak rising from a less resistant eroded plain. The Appalachian National Scenic Trail passes through New Hampshire, and the Saint-Gaudens National Historic Site is located in Cornish.

Major rivers include the 110-mile (177-km) Merrimack River, which bisects the lower half of the state north-south and ends up in Newburyport, Massachusetts. Its major tributaries include the Contoocook River, Pemigewasset River, and Winnipesaukee River. The 410-mile (670-km) Connecticut River, which starts at New Hampshire's Connecticut Lakes and flows south to Connecticut, defines the western border with Vermont. Oddly, the state border is not in the center of that river, as is usually the case, but lies at the low-water mark on the Vermont side; so New Hampshire actually owns the entire river where it runs adjacent to Vermont. The "northwesternmost headwaters" of the Connecticut also define the Canadian border with New Hampshire.

The Piscataqua River and its several tributaries form the state's only significant ocean port where they flow into the Atlantic at Portsmouth. The Salmon Falls River and the Piscataqua define the southern portion of the border with Maine. The state has an ongoing boundary dispute with Maine in the area of Portsmouth Harbor, with New Hampshire claiming dominion over several islands (now known as Seavey Island) that include the Portsmouth Naval Shipyard as well as to the Maine towns of Kittery and Berwick. The largest lake is Lake Winnipesaukee, which covers 72 square miles (186 km²) in the east-central part of New Hampshire.

Hampton Beach is a popular local summer destination. About 10 miles (16 km) offshore are the Isles of Shoals, nine small islands (4 belonging to the state) best known as the site of a 19th century art colony founded by poet Celia Thaxter, as well as the alleged location of one of the buried treasures of the pirate Blackbeard.

It is the second-most-forested state in the country, after Maine, in terms of percentage of land covered by woods. This change was caused by the abandonment of farms during the 20th century as many farmers took wage jobs in urban areas or moved to more productive areas. The return of woodlands from open fields forms the subject of many poems by Robert Frost.

The northern third of the state is locally referred to as "north of the notches" in reference to White Mountain passes that channel traffic, or as "the north country". It contains less than 5% of the state's population, suffers from relatively high poverty rates, and is losing population as the logging and paper industries decline. However, the tourist industry, in particular visitors who go to northern New Hampshire to take advantage of the winter ski season, have helped to offset economic losses from mill closures.

It was one of the thirteen colonies that revolted against British rule in the American Revolution. By the time of the American Revolution, New Hampshire was a divided province. The economic and social life of the Seacoast revolved around sawmills, shipyards, merchant's warehouses, and established village and town centers. Wealthy merchants built substantial homes, furnished them with the finest luxuries, and invested their capital in trade and land speculation. At the other end of the social scale, there developed a permanent class of day laborers, mariners, indentured servants, and even slaves. It was the first state to declare its independence, but the only battle fought there was the raid on Fort William and Mary, December 14, 1774 in Portsmouth Harbor, which netted the rebellion sizable quantities of gunpowder, small arms, and cannon (General Sullivan, leader of the raid, described it as, "remainder of the powder, the small arms, bayonets, and cartouch-boxes, together with the cannon and ordnance stores") over the course of two nights. This raid was preceded by a warning to local patriots the previous day, by Paul Revere on December 13, 1774 that the fort was to be reinforced by troops sailing from Boston. This raid is widely regarded (outside Massachusetts) as the first battle of the Revolutionary War. According to unverified accounts, the gunpowder was later used at the Battle of Bunker Hill, transported there by Major Demerit, who was one of several New Hamphire patriots who stored the powder in their homes until it was transported elsewhere for use in revolutionary activities.

New Hampshire was a Jacksonian stronghold; the state sent Franklin Pierce to the White House in the election of 1852. Industrialization took the form of numerous textile mills, which in turn attracted large flows of immigrants from Quebec (the "French Canadians") and Ireland. The northern parts of the state produced lumber and the mountains provided tourist attractions. After 1960, the textile industry collapsed, but the economy rebounded as a center of high technology and a service provider.

Since 1952, New Hampshire gained national and international attention for its presidential primary held early in every presidential election year. It immediately became the most important testing grounds for candidates for the Republican and Democratic nominations. The media give New Hampshire (and Iowa) about half of all the attention paid to all states in the primary process, magnifying the state's decision power (and spurring repeated efforts by out-of-state politicians to change the rules.)

The New Hampshire General Court is a bicameral legislative body, consisting of the House of Representatives and the Senate. The House of Representatives is the fourth-largest legislative body in the English speaking world with 400 members. Only the US House, the British House of Commons and the Indian Parliament are larger. Presumably because the position pays just $100 per year plus mileage, members are more likely to be retired. A survey published by the Associated Press in 2005 found that nearly half the members of the House are retired, with an average age close to 60. The General Court meets in the New Hampshire State House.

The state's sole appellate court is the New Hampshire Supreme Court. The Superior Court is the court of general jurisdiction and the only court which provides for jury trials in civil or criminal cases. The other state courts are the Probate Court, District Court, and the Family Division. The New Hampshire State Constitution is the supreme law of the state, followed by the New Hampshire Revised Statutes Annotated. The State Constitution is the nation's only state constitution which acknowledges the right of revolution, and one of the few that does not expressly mandate the provision of a public school system.

New Hampshire is also the only state with no mandatory seatbelt law for adults, and also has no motorcycle helmet law for adults nor mandatory vehicle insurance for automobiles. Although the state retains the death penalty for limited crimes, the last execution was conducted in 1939. New Hampshire is the only state that does not mandate public kindergarten, partly out of frugality and lack of funding, and partly out of belief in local control, a philosophy under which towns and cities, not the state, make as many decisions as possible. As of 2005, all but two dozen communities in the state provided public kindergarten.

New Hampshire is a "Dillon Rule" state, meaning that powers not specifically granted to municipalities are retained by the state government. Even so, there is within the state's legislature a strong sentiment favoring local control, particularly with regard to land use regulations. Traditionally, local government in New Hampshire is conducted by town meetings, but in 1995, municipalities were given the option of using an official ballot to decide local electoral and budgetary questions, as opposed to the more open and public town meeting.

New Hampshire is an Alcoholic Beverage Control state, and through the State Liquor Commission it takes in $100 million from the sale and distribution of liquor. The state also leads the country in per capita sales of all forms of alcohol.

New Hampshire experienced a significant shift in its economic base during the last century. Historically, the base was comprised of the traditional New England manufactures of textiles, shoe-making, and small machining shops drawing upon low-wage labor from nearby small farms and from parts of Quebec. Today, these sectors contribute only 2% for textiles, 2% for leather goods, and 9% for machining of the state's total manufacturing dollar value (Source: U.S. Economic Census for 1997, Manufacturing, New Hampshire). They experienced a sharp decline due to obsolete plants and the lure of cheaper wages in the South.

The state has no sales tax, no personal income tax (the state does tax, at a 5 percent rate, income from dividends and interest) and the legislature has exercised fiscal restraint, thereby attracting commuters, light industry, specialty horticulture, retail customers and service firms from other jurisdictions with higher tax policies, notably from neighboring Massachusetts, Vermont and Maine (and to a lesser extent, New York). Efforts to diversify the state's general economy have been ongoing.

Additionally, New Hampshire's lack of a broad-based tax system (aside from the controversial state-wide property tax) has resulted in the state's local communities having some of the nation's highest property taxes. Overall, New Hampshire remains ranked 49th among states in combined average state and local tax burden. Nevertheless, ongoing efforts from unhappy homeowners for property tax relief continues. They have argued that residents of Massachusetts and other neighboring states are shopping in New Hampshire tax free, and New Hampshire homeowners are paying them for the privilege.