The chart below shows the information graphically, with the most recent results on the right. It shows the popularity in terms of seats won, of the Australian Labor Party (red) and the Nationalist Party and its predecessors (mid-blue) in the first half of the 20th century, as well as the emergence of the Country Party (green) in 1914, with whom the Nationalists and later the Liberals formed a coalition in order to form government. Two distinct periods were characterised by one party or coalition's dominance—the Labor Party won six of the seven elections between 1924 and 1947, and the Liberal Party (dark blue) in coalition with the Country Party won seven of the eight elections between 1959 and 1983. Occasional internal splits within the Country Party, now known as the Nationals, are also shown on the chart in differing shades of green.
The table below shows the total number of seats won by the major political parties at each election. The totals of the winning party or coalition are shown in bold, while other parties in government are shown in bold italic. Full details on any election are linked via the year of the election at the start of the row.
Until the 1904 election, most candidates did not belong to political parties. However, some candidates declared their support for the administration of the time, while others declared their opposition to it. Full details on any election are linked via the year of the election at the start of the row.
C The party was known as the Country Party (1914–1946; 1962–1973), Country and Democratic League (1946–1962), National Alliance (1974), National Country Party (1975–1984) and National Party (1984–present). A separate National Party existed from 1978–1984 and is shown under "Other Parties".
D The National Labor Party were a split from the Labor Party which sat in coalition with the Nationalists between 1917 and 1924.
Two features of the Western Australian electoral system are worthy of note in interpreting election results. The first is that until the 1974 election, many seats in both houses were uncontested—usually more than one-quarter of all seats on offer. Since 1974, only three seats have been uncontested—that being the seats of Collie and East Melville in the 1980 election, when the rival party's candidates missed the nomination deadline and hence could not stand, and the seat of Narrogin in the 1983 election.
The second feature is malapportionment, which until 2008 was a significant feature of the Western Australian political landscape. Seats in metropolitan and rural areas did not contain the same number of electors—as at 30 September 2007, a Member of the Legislative Assembly represented either 28,519 metropolitan voters within the Metropolitan Region Scheme area, or 14,551 country voters. This was believed to disproportionately favour the Nationals in terms of parliamentary representation. Reforms enacted in 2005 which took effect at the 2008 election produced an average district enrolment of 21,350, which applied to all but five of the 59 districts created in the 2007 redistribution. An allowance remained for particularly large districts—those of 100,000 square kilometres (39,000 sq mi) or more, located in the north and east of the State—in the form of a Large District Allowance.
^de Garis, Brian (1991). "Self-Government and the Emergence of Political Parties 1890–1911". In Black, David. The House on the Hill: A history of the Parliament of Western Australia. Parliament of Western Australia. pp. 81–82. ISBN0-7309-3983-9.
^Black, David (1981). "The Era of Labor Ascendancy 1924–1947". In Stannage, Tom. A New History of Western Australia. University of Western Australia Press. p. 439. ISBN0-85564-170-3.
^ abcIn 1923, the Country Party split into the Ministerial Country Party (MCP), with 15 members, and the Executive Country Party (ECP), with 3. At the 1924 election, the MCP won 7 seats and the ECP won 6—subsequently, the MCP merged with the Nationalists while the ECP reverted to the name Country Party. In 1978, a disagreement between those favouring coalition with the Liberals and those favouring independence resulted in the latter group splitting to form the National Party, while the original party remained as the National Country Party. In 1984, the two parties reunited, although the three NCP members ultimately joined the Liberal Party, with two of them losing to endorsed Nationals at the 1986 election. The Executive Country (1924) and National (1978–1984) parties are shaded light green in this list.