[2] The county is named for Robert Anderson Irion, a secretary of state of the Republic of Texas.

[3] In 1876, John Arden brought the first flock of sheep from California, and Billy Childress established the Longhorn 7D Ranch.

[7] In 2020 Irion was the slowest county to comply with the Supreme Court's Obergefell v. Hodges ruling, forbidding the ban on same-sex marriages.

[8] The Spraberry Trend, the third-largest oil field in the United States by remaining reserves, underlies much of the county.

As of 2017, only Irion County among those in Texas had stated it would refuse to issue licenses to same-sex couples.

Many counties started issuing same-sex marriage licenses within hours of the Obergefell ruling on June 26, 2015, while others awaited direction from state officials, local county attorney advice, or issuance of corrected state marriage license forms.

[17][18] Irion County was the sole holdout in Texas, with reports that the situation was still in effect two years later.

It has not voted for a Democratic presidential candidate since Texas native Lyndon B. Johnson won a statewide and national landslide in 1964.