Oklahoma was admitted to the Union on November 16, 1907. The 2 senators from this state are in 2 different classes. A class gets re-elected every 2 years. For example, Class 3 got re-elected in 2010, Class 1 got re-elected in 2012, and Class 2 got re-elected in 2014. Then the cycle will start over with Class 3 getting re-elected in 2016.