Australia became a federated nation in 1901.
On January 1, 1901, six self-governing British colonies—New South Wales, Queensland, South Australia, Tasmania, Victoria, and Western Australia—united to form the Commonwealth of Australia. This process is known as the Federation of Australia, and it created a national government while allowing the new states to retain their own parliaments and many local powers.
The federation movement developed over several decades. Supporters argued that a united Australia could coordinate defense, immigration, customs, trade, and other matters more effectively than separate colonies. The Australian Constitution provided the legal framework for the new federal system and came into force on the federation date.
A common mix-up is confusing federation with the opening of Australia’s first federal Parliament. The Commonwealth began on January 1, but Parliament did not formally open until May 9, 1901, in Melbourne. Edmund Barton became the first prime minister of the new Commonwealth.