The seat of Mayo is named after Helen Mayo (1878-1967), founder of the Mothers and Babies Health Association and the first woman to be elected to a University Council in Australia.
In December 2003 the Electoral Commission for South Australia announced new boundaries for the federal electorate divisions in South Australia and these changes took effect at the October 2004 Federal Election.
Mayo is now the third largest electorate in the state with an area of 9,190 sq km and a projected population of 96,770.
It is very much a seat with a rural and semi-rural character and a strong emphasis on wine, tourism and agriculture.
Major townships include Victor Harbor, Strathalbyn, Mount Barker, Aberfoyle Park, and Stirling/Aldgate/Bridgewater.