Elections since the 1930s have been dominated by two political parties, National and Labour. Between March 2005 and August 2006, New Zealand became the first country in the world in which all the highest offices in the land – head of state, governor-general, prime minister, speaker, and chief justice – were occupied simultaneously by women. The current prime minister is Jacinda Ardern, who has been in office since 26 October 2017. She is the country's third female prime minister.