City of Penrith: Council history
The Municipality of Penrith was incorporated on 12 May 1871 under the Municipalities Act 1858 (NSW). On 3 March 1890, St Marys was separately incorporated, and on 26 July 1893 and 9 September 1895, Mulgoa and Castlereagh followed respectively. In 1913, Mulgoa became the "A" Riding of the neighbouring Nepean Shire.
On 1 January 1949, under the Local Government (Areas) Act 1948, the Municipalities of Penrith, St Marys and Castlereagh and A Riding of the Nepean Shire amalgamated to form a new Municipality of Penrith. It was declared a City on 21 October 1959, and expanded westwards to include Emu Plains and Emu Heights, formerly part of the City of Blue Mountains, on 25 October 1963.