Arizona was admitted to the Union on February 14, 1912. U.S. senators from Arizona belong to class 1 and class 3 and are popularly elected for a six-year term beginning January 3. Elections are held the first Tuesday after the first Monday in November. The state's current U.S. senators are Independent Kyrsten Sinema, serving since 2019, and Democrat Mark Kelly, serving since 2020. Carl Hayden was the longest serving senator, served from 1927 to 1969. Arizona is one of fifteen states alongside Colorado, Florida, Georgia, Hawaii, Idaho, Indiana, Louisiana, Maine, Massachusetts, Minnesota, Missouri, Nevada, South Dakota and Utah to have a younger senior senator and an older junior senator. In total, only 14 individuals have ever served as a Senator from Arizona.