Boulder is a suburb in the Western Australian Goldfields, 595 kilometres (370 mi) east of Perth and bordering onto the city of Kalgoorlie in the Eastern Goldfields region. The Boulder (horse) Races were a significant event in early twentieth century goldfields region history. The town maintained its separation from Kalgoorlie until the 1980s, however even prior to that era, many surveys and studies of the towns and their areas tended to join the names. Prior to 1989, Boulder was a town, but it was merged with Kalgoorlie to form the City of Kalgoorlie–Boulder.