Greg Gianforte, the governor of Montana, ratified a statute that is anti-transgender.
The proposed legislation forbids transgender athletes from joining school sports teams that reflect their gender identification.
Despite criticism from the transgender community and their allies, the governor's decision was made.
John Fuller, a Republican state representative, presented the measure.
Several states, including Montana, have recently passed legislation of a similar nature.
The measure has come under fire for prejudice against young transgender people.
The governor's transgender son had requested that he reject the measure, but in vain.
Advocates are anticipated to file legal challenges to the measure.