As of the census of 2010, there were 8,437 people, 3,188 households, and 2,152 families living in the county.

[11] As of the census of 2000, there were 8,547 people, 3,117 households, and 2,266 families living in the county.

24.5% of all households were made up of individuals, and 7.3% had someone living alone who was 65 years of age or older.

As the county was heavily unionized and the Democratic Party was generally the party of organized labor, Greenlee County voted for the Democratic nominee in every presidential election from the state's admission to the Union in 1912 to 1996, being one of only seven Mountain State counties to support George McGovern in his landslide defeat against Republican Richard Nixon in 1972.

However, in 2000, George W. Bush became the first Republican presidential candidate to win the county, and it has voted for the Republican nominee in the five elections since, giving Donald Trump 66% of the vote in 2020.

The county's turn to the GOP can likely be explained by the Democratic Party's modern platform of environmentalism that has been perceived as anti-mining (for example, Bush's 2000 opponent, Al Gore, was staunchly against coal mining).

[13][14] Greenlee County continued to shift right in 2024, with Kamala Harris becoming the first Democrat in history to fail to break 30%.

The county is located in Arizona's 6th congressional district, which has a Cook Partisan Voting Index of R+3 and is represented by Republican Congressman Juan Ciscomani.

[17] In the Arizona Senate it is represented by Republican Gail Griffin.

[18] The population ranking of the following table is based on the 2010 census of Greenlee County.