What nickname was given to settlers who tried to enter Oklahoma before it was officially opened?

The nickname given to settlers who ventured into Oklahoma before its official opening was "Sooners." This term specifically refers to individuals who illegally crossed into the land prior to the designated start time of the land rush in 1889. The Sooners took advantage of the confusion surrounding the opening, often arriving early to stake their claims, which led to their distinctive nickname.

On the other hand, the term "Boomers" refers to those who advocated for the opening of the lands in Oklahoma and sought to enter lawfully but did not go in before the official opening date. "Pioneers" is a more general term used to describe any early settlers who moved into new territories, while "Fronters" is not a commonly recognized term associated with this period in American history. The uniqueness of the name "Sooners" specifically ties to the actions of these early arrivers during the land rush era.