[3] The boundary was then extended eastward to the San Carlos River by public petition in 1889.

[4] In the 1880s, a long range war broke out in Gila County that became the most costly feud in American history, resulting in an almost complete annihilation of the families involved.

Once partisan feelings became tense and hostilities began, Frederick Russell Burnham, who later became a celebrated scout and the inspiration for the boy scouts, was drawn into the conflict on the losing side.

[5][6] Burnham shot many men in the feud, and was himself nearly killed by a bounty hunter.

[7] Tom Horn, an infamous assassin, was known to have taken part as a killer for hire, but it is unknown which side employed him.

[citation needed] In the 1960s, it was home of Gerald Gault, who was the subject of the 1967 U.S. Supreme Court ruling, in re Gault, that stated juveniles have the same rights as adults when arrested to be notified of the charges against them, the rights to attorneys, for family members to be notified of their arrests and to confront their accusers and to not be punished more harshly than adults who are convicted of the same crime, especially if an adult's penalty for the crime would be less than that accorded a juvenile convict.

25.8% of all households were made up of individuals, and 12.3% had someone living alone who was 65 years of age or older.

Historically, Gila County was a Democratic-leaning county in largely-Republican Arizona – for example, it voted for Adlai Stevenson II in 1952, Hubert Humphrey in 1968 and (very narrowly in a three-way contest) for John W. Davis in 1924.

Only during very large Presidential landslides was Gila County carried by Republicans before 2000: indeed, apart from Ronald Reagan in 1980 and Richard Nixon in 1972, no Republican before 2000 ever carried the county by more than seven percentage points.

Moreover, Barack Obama did worse here in 2008 than John Kerry did in 2004, one of a few non-Ozark or non-Appalachian counties where this occurred (possibly due to Arizona Senator John McCain's presence on the ballot).

Gila County was covered in the papers[23] as the site of a confluence between politics and public health as the conservatism of the county (with Democrat Joe Biden losing by 34 points in the 2020 presidential election[24]) was considered one reason for vaccine skepticism, allowing the county to distribute COVID-19 vaccines to all adults well before other areas in the US.