[3][4] It derives its name from a Chelan Indian word meaning "deep water," likely a reference to 55-mile (89 km)-long Lake Chelan, which reaches a maximum depth of 1,486 feet (453 m).

Chelan County is part of the Wenatchee, Washington, Metropolitan Statistical Area.

As of the 2010 census, there were 72,453 people, 27,827 households, and 18,795 families living in the county.

[14] As of the 2000 census,[15] there were 66,616 people, 25,021 households, and 17,364 families living in the county.

16.9% were of German, 11.2% English, 9.3% United States or American and 7.1% Irish ancestry.

25.10% of all households were made up of individuals, and 10.80% had someone living alone who was 65 years of age or older.

Chelan County is part of the 8th Congressional District federally, represented by Democrat Kim Schrier.

Formerly a Republican Party stronghold, it has narrowed up considerably in recent years, with Donald Trump only carrying the county by around 8 points over Joe Biden in 2020.