[2] Campbell County comprises the Gillette, WY Micropolitan Statistical Area.

[3] It was named either for John Allen Campbell, a governor of the Wyoming Territory, or for Robert Campbell, a trapper and fur trader associated with William Henry Ashley.

[5] As of the 2000 United States Census,[9] there were 33,698 people, 12,207 households, and 9,008 families in the county.

20.20% of all households were made up of individuals, and 3.90% had someone living alone who was 65 years of age or older.

As of the 2010 United States Census, there were 46,133 people, 17,172 households, and 11,933 families in the county.

[10] In terms of ancestry, 32.2% were German, 15.9% were Irish, 10.8% were English, 5.5% were American, and 5.1% were Norwegian.

No Democratic presidential candidate has carried Campbell County since Franklin D. Roosevelt won 46 of 48 contemporary states against Alf Landon in 1936.

Since 1950, the only Democrat to have won forty percent of the county's vote is Lyndon Johnson in his 1964 landslide victory against Barry Goldwater, and in the subsequent half-century no Democrat has passed one-third of the county's vote.