The only city in Coös County is Berlin, with the rest of the communities being towns, or unincorporated townships, gores and grants.

The southernmost portion of the county is part of the White Mountains Region and is home to Mount Washington.

The two-syllable pronunciation is sometimes indicated with a diaeresis, notably in the Lancaster-based weekly newspaper The Coös County Democrat and on some county-owned vehicles.

During the American Revolutionary War two units of troops of the Continental Army — Bedel's Regiment and Whitcomb's Rangers — were raised from the settlers of Coös.

From the Treaty of Paris of 1783 until 1835, the boundaries in the northern tip of the county (and New Hampshire itself) were disputed with Lower Canada (which was soon to become part of the Province of Canada), and for some years residents of the area formed the independent Republic of Indian Stream.

In the 1810 census, there were 3,991 residents, and by 1870 there were nearly 15,000, at which point the entire county was valued at just under $5 million, with farm productivity per acre comparing favorably with that of contemporary Illinois.

[6] It is the largest county in New Hampshire by area, and borders both Vermont and Maine, as well as Canada.

Much of its mountainous area is reserved as national forest, wilderness, state parks and other public areas; these encompass most of the northern portion of the White Mountains, including all the named summits of the Presidential Range (though one, Mt.

Coös County is the least populated of all New Hampshire counties, and the only one with significant amounts of unincorporated land; over half of the municipal-like entities are unincorporated townships, gores, or grants, a rarity in New Hampshire, where nearly all of the land is incorporated as towns or cities.

The exceptions were 1968, 2004, and 2020, when it supported Hubert Humphrey over Richard Nixon, John Kerry over George W. Bush, and Donald Trump over Joe Biden, respectively.

[22] (Compiled from Radiostationworld.com) Some stations from nearby Sherbrooke can also be received in Coös County, the strongest being CITE-FM-1 102.7 FM.

Cable companies carry local market stations WPFO (Fox), WMTW (ABC), WGME (CBS), and WCSH (NBC), plus NHPTV, WMUR and select stations from the Burlington / Plattsburgh market.

Robert Frost, who once lived in Franconia in neighboring Grafton County, wrote the poem "The Witch of Coös".