It was named in honor of Charles Carroll of Carrollton,[3] who had died in 1832, the last surviving signer of the United States Declaration of Independence.

A salient along the northwestern margin of the county runs through Crawford Notch; the northern portion of the salient is within Crawford Notch State Park.

As of the census[10] of 2000, there were 43,666 people, 18,351 households, and 12,313 families living in the county.

The population density was 18 people per square kilometre (47 people/sq mi).

22.5% were of English, 15.6% Irish, 10.5% American, 9.7% French, 6.7% German, 5.8% Italian and 5.2% Scottish ancestry.

26.60% of all households were made up of individuals, and 11.10% had someone living alone who was 65 years of age or older.

As of the 2010 United States census, there were 47,818 people, 21,052 households, and 13,569 families living in the county.

[16] This made him the first Democratic presidential nominee to win the county since 1912 and the first Democratic presidential nominee to win an absolute majority in the county since 1884.

The county is politically divided between the more conservative southern half, home to several seasonal communities along the north shore of Lake Winnipesaukee including Moultonborough, Tuftonboro, and Wolfeboro, and the more liberal northern half, with several ski towns and resort towns such as Bartlett and Conway.

In both the 2012 Presidential and gubernatorial elections in New Hampshire, Democratic candidates easily won the northern half of the county, and Republican candidates easily won the southern half of the county.