During this period, the boundaries were changed twice, in 1976 and 1987, with the riding now consisting of southern and central Oshawa.

In the early 1990s, the unpopularity of both the NDP and the Progressive Conservatives (PCs) caused the Liberals to win the seat throughout the 1990s.

In the elections following 2004, the Conservatives continued to increase their share of the vote, as did the NDP to a lesser extent, at the expense of the Liberals.

[3][4] The riding has a much lower proportion of visible minorities compared to the rest of the province.

[4][5] The riding had historically been dominated by a working-class electorate, but the loss of auto industry jobs in the area since the 1980s has lessened the influence of the working class.

"[7][8] In the Ontario riding, the previous election was competitive, with the PCs, Liberals, and NDP all being within about 6500 votes (10%) of each other.

[9][10] Shortly afterward, Prime Minister Pierre Trudeau invited Broadbent to join his cabinet, who rejected his offer.

[15] In 1984, Broadbent held on to the seat by a margin of 2000 votes despite the PCs' national landslide victory.

Longfield proposed, citing support from MP Ivan Grose and Oshawa City Council, that the district be changed from the previous version to not include the area west of Simcoe Street north of Rossland Road and the Oshawa Creek north of former Highway 2, but include the area east of Simcoe Street up to Winchester Road.

[citation needed] The NDP nominated Sid Ryan, a well-known labour leader.

These gains were at the expense of the Liberals, likely due to the recent layoffs at the General Motors Oshawa plant.

[27][28][29] The Conservatives would once again increase their vote percentage in the 2008 election and by a higher amount than the NDP, at the expense of the Liberals.

[6] In the run-up to that year's election, a writer for the National Post considered it to be a potential NDP pickup.

[34] MPs Erin O'Toole and Colin Carrie later objected, requesting that as much of Oshawa as possible be kept within one electoral district, adding 2 campuses.

[39] By the 2019 election, Carrie had become the Shadow Cabinet Secretary for Canada-US relations and Economic Development in Southern Ontario.

[40] In April 2019, Forum Research conducted a poll in the riding showing a larger Conservative lead and a large NDP decline.

[43] According to the 2021 Canadian census[44] Ethnic groups: 73.8% White, 7.8% Black, 5.3% South Asian, 4.6% Indigenous, 2.4% Filipino, 1.3% Latin American, 1.0% Chinese Languages: 83.6% English, 1.7% French, 1.0% Spanish Religions: 52.2% Christian (22.7% Catholic, 6.0% United Church, 4.6% Anglican, 1.9% Pentecostal, 1.6% Baptist, 1.3% Christian Orthodox, 1.2% Presbyterian, 12.9% Other), 3.9% Muslim, 1.7% Hindu, 40.6% None Median income: $39,600 (2020) Average income: $47,520 (2020) This riding has elected the following members of Parliament: