On what date did the Australian colonies federate to form the Commonwealth of Australia?

The Australian colonies federated to form the Commonwealth of Australia on 1 January 1901.

Federation united six self-governing British colonies: New South Wales, Victoria, Queensland, South Australia, Western Australia, and Tasmania. They became the states of the new Australian federation, with a national government operating under the Australian Constitution.

The Commonwealth of Australia Constitution Act 1900 was passed by the British Parliament and received royal assent before federation began. The Constitution took effect on 1 January 1901, and the Commonwealth was formally proclaimed at a ceremony in Sydney’s Centennial Park. Edmund Barton became the first prime minister.

This date is sometimes confused with Australia Day, which falls on 26 January and commemorates the arrival of the First Fleet in 1788. Federation Day concerns the creation of Australia’s federal Commonwealth, while Australia Day marks a much earlier colonial event.