Northumberland—Peterborough South was created by the 2012 federal electoral boundaries redistribution and was legally defined in the 2013 representation order. It came into effect upon the call of the 42nd Canadian federal election, scheduled for 19 October 2015. 77% of the riding was formed from Northumberland—Quinte West, 13% from Durham and 10% from Peterborough.

The riding was originally intended to be named Northumberland—Pine Ridge.

Under the 2022 Canadian federal electoral redistribution the riding will be renamed Northumberland—Clarke at the next federal election.

Geography

The riding is located in Central Ontario along Lake Ontario. It contains the entirety of Northumberland County, southern Peterborough and the eastern half of the municipality of Clarington.

Demographics

According to the 2021 Canadian census

Ethnic groups: 89.8% White, 5.1% Indigenous, 1.2% Black, 1.1% South Asian
Languages: 92.6% English, 1.3% French
Religions: 54.1% Christian (17.6% Catholic, 11.3% United Church, 7.6% Anglican, 2.4% Presbyterian, 1.8% Baptist, 1.2% Pentecostal, 12.2% Other), 43.8% None
Median income: $41,600 (2020)
Average income: $53,100 (2020)

Members of Parliament

This riding has elected the following members of Parliament:

Election results

Graphs are unavailable due to technical issues. There is more info on Phabricator and on MediaWiki.org.

v t e 2021 Canadian federal election
Party	Candidate	Votes	%	±%	Expenditures
	Conservative	Philip Lawrence	31,015	44.5	+4.8	$102,345.39
	Liberal	Alison Lester	23,336	33.5	-2.7	$114,472.38
	New Democratic	Kim McArthur-Jackson	9,809	14.1	+0.2	$7,800.16
	People's	Nathan Lang	3,813	5.5	+3.4	$7,035.54
	Green	Christina Wilson	1,764	2.5	-5.5	$3,692.08
Total valid votes			69,737
Total rejected ballots			459
Turnout			70,196	69.98
Eligible voters			100,308
Source: Elections Canada

2021 federal election redistributed results
Party		Vote	%
	Conservative	27,553	43.99
	Liberal	21,311	34.02
	New Democratic	8,735	13.95
	People's	3,430	5.48
	Green	1,608	2.57

v t e 2019 Canadian federal election
Party	Candidate	Votes	%	±%	Expenditures
	Conservative	Philip Lawrence	27,385	39.7	+0.14	$68,864.16
	Liberal	Kim Rudd	24,977	36.2	-6.31	$83,715.67
	New Democratic	Mallory MacDonald	9,615	13.9	-0.9	$8,871.55
	Green	Jeff Wheeldon	5,524	8.0	+4.87	none listed
	People's	Frank Vaughan	1,460	2.1	–	$1,643.34
Total valid votes/expense limit			68,961	100.0
Total rejected ballots			484
Turnout			69,445	71.7
Eligible voters			96,841
	Conservative gain from Liberal		Swing		+3.23
Source: Elections Canada

2015 Canadian federal election
Party	Candidate	Votes	%	±%	Expenditures
	Liberal	Kim Rudd	27,043	42.51	+21.42	$114,323.76
	Conservative	Adam Moulton	25,165	39.56	-13.80	$135,349.14
	New Democratic	Russ Christianson	9,411	14.80	-5.79	$41,225.56
	Green	Patricia Sinnott	1,990	3.13	-1.55	$1,350.03
Total valid votes/Expense limit			63,609	100.00		$229,426.74
Total rejected ballots			267	0.42	–
Turnout			63,876	71.67	–
Eligible voters			89,128
	Liberal gain from Conservative		Swing		+17.61
Source: Elections Canada

2011 federal election redistributed results
Party		Vote	%
	Conservative	29,377	53.37
	Liberal	11,611	21.09
	New Democratic	11,331	20.58
	Green	2,576	4.68
	Others	154	0.28