Perth formally became part of the Federation of Australia in 1901, joining as the last colony after securing concessions, including a transcontinental railway linking Perth with South Australia. The early 20th century saw restrictive policies, including a ban on Indigenous people entering major parts of the city from 1927 to 1954. In 1933, a referendum showed strong support for secession, yet political realities and legal barriers prevented the state from separating from the rest of Australia.

After World War II, Perth had a population of roughly 280,000 and an economy that had stagnated since the 1920s. State governments implemented a program of post-war economic development led by public works planners such as Russell Dumas. Key projects included the expansion of the Mundaring and Wellington dams, development of Perth Airport, and establishment of an industrial zone at Kwinana. Economic growth was further fueled by post-war immigration and foreign investment, including the Anglo-Iranian Oil Refinery constructed in the early 1950s.

The city’s urban design shifted in the 1950s, guided by the Stephenson-Hepburn Report, which encouraged development along highway networks and the gradual closure of tram systems. Perth’s mining-pastoral boom in the 1960s accelerated population growth and urban expansion. In 1962, the city earned international attention as residents illuminated their homes to celebrate astronaut John Glenn’s orbit, earning the nickname “City of Light,” a tradition repeated in 1998 for the Space Shuttle.

Perth’s prosperity is closely tied to its role as the service center for Western Australia’s vast resource sector, including gold, iron ore, nickel, and natural gas. The 1990s and 2000s saw administrative restructuring, population growth, and major infrastructure projects such as the Perth Convention and Exhibition Centre and the mixed-use Elizabeth Quay waterfront precinct, cementing Perth’s status as a modern, vibrant urban center.