Barcaldine (locally ) is a small town in Central West Queensland, Australia, approximately by road west of the city of Rockhampton. The town is situated on Lagoon Creek, which flows into the Alice River approximately five kilometres south of the Barcaldine. This is the administrative centre of the Barcaldine region. Major industries are sheep and beef cattle rearing. The town takes its name from a sheep station called Barcaldine Downs, which was named for Barcaldine, Argyll and Bute, Scotland. At the 2006 census, Barcaldine had a population of 1,337.
Barcaldine played a significant role in the Australian labour movement and the birth of the Australian Labor Party. In 1891, it was one of the focal points of the 1891 Australian shearers' strike, with the Eureka Flag flying over the strike camp. The landmark Tree of Knowledge, under which the strikers met, stood outside the railway station. In 2006, persons unknown poisoned the tree with the herbicide Roundup, which led to its demise.
One of the first May day marches in the world took place during the strike on 1 May 1891 in Barcaldine. The Sydney Morning Herald reported that of the 1,340 men that took part, 618 were mounted on horses. Banners carried included those of the Australian Labor Federation, the Shearers' and Carriers' Unions, and one inscribed 'Young Australia'. The leaders wore blue sashes and the Eureka Flag was carried. The Labor Bulletin reported that cheers were given for "the Union", "the Eight-hour day", "the Strike Committee" and "the boys in gaol". It reported the march: