How did the sooners get their name?

Answer 1

The name refers to the early land rushes that opened the Oklahoma Indian Territory up to non-native owners.

There were seven land rushes from 1889 to 1895. The movie "Far and Away" depicts a land rush.

The name itself comes from the "sooner clause" of the Indian Appropriations Act which basically said that a person who entered and occupied the land sooner than the government-assigned start time to the rush would be denied the claim to the land. The term "Sooners" describes those who cheated, and possessed the land early, usually camping out in a low lying area near the claim stake in order to claim the land as soon as the start time passed.

"Boomers" is a related term that refers to white settlers that had illegally occupied Unassigned Land prior to a land rush in the mistaken belief that they were unincorporated public lands open to any claim of settlement under the 1862 Homestead Act.

Ironically, the phrase "Boomer Sooner" is a modern phrase that originally meant an illegal, land-stealing cheat.

This is not a improved answer but here.....originally called "moonshiners" Sooners was the name given to the settlers in the Midwest. They decided to adopt the nickname because of the location of OU in the Midwest.