Which Australian colony was the last to join Federation?

Western Australia was the last Australian colony to join Federation. WA voted Yes in its federation referendum on 31 July 1900 (44,800 Yes to 19,691 No), more than a year after the other colonies had voted. The Commonwealth of Australia Constitution Act 1900 had already been passed by the British Parliament on 5 July 1900 and given royal assent by Queen Victoria on 9 July 1900, with the intention that WA would have joined or that the Act would take effect for the other five colonies regardless.

Several factors made WA the late joiner. Geographic isolation: Perth was about 3,400 kilometres from Sydney, with limited communication and travel connections. The colony had only recently gained responsible government (in 1890, much later than the eastern colonies). Economic distinctiveness: WA's gold rush from 1893 onwards produced wealth and a sense of self-sufficiency, and the colony depended on tariffs from imported goods that federal customs union would end. Local concerns about federal control of railways and the new transcontinental link added political resistance.

Several specific concessions helped WA join. The Constitution allowed WA to maintain its import duties at progressively reducing rates for five years after federation (a special transitional arrangement that no other colony received). The Commonwealth committed to building a transcontinental railway from Port Augusta in South Australia to Kalgoorlie in Western Australia (delivered as the Trans-Australian Railway, completed in 1917). The promise of federal defence and the developing fear of Asian powers strengthened the argument for joining.

The political debate inside WA was fierce. The eastern goldfields communities (centred on Kalgoorlie and Coolgardie) were strongly Yes, with the Goldfields Reform League threatening to secede from WA and form a new colony (Auralia) to join federation if WA did not. The Perth-based establishment, particularly Premier John Forrest, negotiated hard for concessions. The eventual Yes vote of about 70 per cent was decisive. WA joined Federation on 1 January 1901 alongside the other five colonies, but the secessionist sentiment in WA continued: a 1933 WA referendum on secession from Australia produced a 68 per cent Yes vote, although the British Parliament refused to act on it. WA's special regional character and distance from the eastern states remain features of Australian federation today.