This suburban area had leaned Progressive Conservative from 1979 until 1993 when it swung hard to the Liberals primarily due to the rapid growth of the Greater Toronto Area and high immigrant populations, just like the suburbs to the north of Toronto.
In 2011 they were shut out of the region, but nearly won Mississauga East—Cooksville, losing it by fewer than 700 votes.
In 2015, 2019 and 2021 Canadian federal elections, the Liberals won all ridings in Mississauga, Brampton, and Oakville.
The Conservatives came within 5 points of winning Brampton West, their best seat in 2004, thanks to star candidate Tony Clement.
When they swept the region in 2011, Oakville was the only riding where they won a majority of the vote (54%).