Australia is a federal parliamentary constitutional monarchy. The country has maintained a stable liberal democratic political system under its constitution, which is one of the world's oldest, since Federation in 1901. It is also one of the world's oldest federations, in which power is divided between the federal and state and territorial governments. The Australian system of government combines elements derived from the political systems of the United Kingdom (a fused executive, constitutional monarchy and strong party discipline) and the United States (federalism, a written constitution and strong bicameralism with an elected upper house), along with distinctive indigenous features.