The Commonwealth inherited responsibility from the colonies for communications under the Constitution in 1901. With the establishment of the Postmaster-General's Department (PMG), the Commonwealth Government assumed control of existing communication networks across Australia, including postal and telegraphic services. The Wireless Telegraphy Act 1905 established the Commonwealth's control of wireless technology. The Commonwealth developed infrastructure in response to population growth, events such as world wars and improvements in technology. The Archives holds a wide array of records that relate to communications in South Australia, such as correspondence, plans, photographs, posters and technical files.