Big Stone County is a county in the U.S. state of Minnesota. As of the 2020 census, the population was 5,166. Its county seat is Ortonville.

The county was formed in 1862, and was organized in 1874. It is named for Big Stone Lake.

Big Stone County lies on the western side of Minnesota. Its southwest boundary line abuts the east boundary line of the state of South Dakota. The Little Minnesota River flows along the county's southwestern boundary. Since 1937, a dam (Big Stone Lake Dam) has impounded the river's waters, creating Big Stone Lake. Water flowing out from this lake flows along the south boundary line of the county, and is known as the Minnesota River from that point. Fish Creek flows southwesterly through the northwestern part of the county, discharging into Big Stone Lake at the county's southwestern boundary.

The terrain of Big Stone County is low rolling hills, wooded or devoted to agriculture. The terrain generally slopes to the south and east, although its southwestern portion slopes to the river valley. Its highest point is on its north line near the northwestern corner, 2.9 miles (4.7 km) east of Lagoona Beach, at 1,201 ft (366 m) ASL. The county has a total area of 528 square miles (1,370 km), of which 499 square miles (1,290 km) is land and 29 square miles (75 km) (5.5%) is water.

Source: United States Census Bureau 2007 TIGER/Line Shapefiles

Ortonville, Minnesota
Climate chart (explanation)
J F M A M J J A S O N D     0.6     23 1     0.6     27 7     1.4     39 19     2.6     56 32     2.5     69 45     3.6     78 56     3.9     84 60     2.7     82 58     2.6     73 47     2.2     59 34     1     41 21     0.4     25 7 █ Average max. and min. temperatures in °F █ Precipitation totals in inches Source: The Weather Channel
Metric conversion J F M A M J J A S O N D     15     −5 −17     14     −3 −14     35     4 −7     67     13 0     64     21 7     90     26 13     98     29 16     69     28 14     66     23 8     57     15 1     25     5 −6     11     −4 −14 █ Average max. and min. temperatures in °C █ Precipitation totals in mm

In recent years, average temperatures in the county seat of Ortonville have ranged from a low of 1 °F (−17 °C) in January to a high of 84 °F (29 °C) in July, although a record low of −44 °F (−42 °C) was recorded in February 1994 and a record high of 108 °F (42 °C) was recorded in July 1966. Average monthly precipitation ranged from 0.43 inches (11 mm) in December to 3.85 inches (98 mm) in July.

Historical population

Census	Pop.	Note	%±
1870	24		—
1880	3,688		15,266.7%
1890	5,722		55.2%
1900	8,731		52.6%
1910	9,367		7.3%
1920	9,766		4.3%
1930	9,838		0.7%
1940	10,447		6.2%
1950	9,607		−8.0%
1960	8,954		−6.8%
1970	7,941		−11.3%
1980	7,716		−2.8%
1990	6,285		−18.5%
2000	5,820		−7.4%
2010	5,269		−9.5%
2020	5,166		−2.0%
2023 (est.)	5,105		−1.2%
U.S. Decennial Census 1790-1960 1900-1990 1990-2000 2010-2020

Big Stone County Racial Composition

Race	Num.	Perc.
White (NH)	4,809	93.1%
Black or African American (NH)	19	0.37%
Native American (NH)	34	0.66%
Asian (NH)	12	0.23%
Pacific Islander (NH)	4	0.07%
Other/Mixed (NH)	148	2.7%
Hispanic or Latino	140	2.7%

As of the census of 2000, there were 5,820 people, 2,377 households, and 1,611 families in the county. The population density was 11.7 per square mile (4.5/km). There were 3,171 housing units at an average density of 6.35 per square mile (2.45/km). The racial makeup of the county was 98.44% White, 0.17% Black or African American, 0.52% Native American, 0.41% Asian, 0.12% from other races, and 0.34% from two or more races. 0.34% of the population were Hispanic or Latino of any race. 45.7% were of German, 21.0% Norwegian, 8.0% Swedish and 6.3% Irish ancestry.

There were 2,377 households, out of which 29.00% had children under the age of 18 living with them, 59.60% were married couples living together, 5.30% had a female householder with no husband present, and 32.20% were non-families. 30.20% of all households were made up of individuals, and 16.90% had someone living alone who was 65 years of age or older. The average household size was 2.38 and the average family size was 2.97.

The county population contained 24.80% under the age of 18, 5.30% from 18 to 24, 21.90% from 25 to 44, 24.00% from 45 to 64, and 24.00% who were 65 years of age or older. The median age was 44 years. For every 100 females there were 94.30 males. For every 100 females age 18 and over, there were 91.10 males.

The median income for a household in the county was $30,721, and the median income for a family was $37,354. Males had a median income of $27,857 versus $20,123 for females. The per capita income for the county was $15,708. About 7.80% of families and 12.00% of the population were below the poverty line, including 14.50% of those under age 18 and 8.80% of those age 65 or over.

Between 1928 and 2008, Big Stone County voted Democratic in every election except for two nationwide Republican landslides in 1952 and 1980. The only other time between 1928 and 2000 that the Republican candidate lost by less than 10% was Ronald Reagan during his 1984 landslide reelection. Beginning in 2000, the Democratic margins began to shrink, with George W. Bush losing by about 2% in both 2000 and 2004, and by a margin of no more than 60 votes. Despite favoring Barack Obama by over 6% in 2008, this would prove to be the most recent time Big Stone County would vote Democratic. Mitt Romney narrowly carried the county by 40 votes and less than 1.5% in 2012. But in 2016, Donald Trump greatly expanded the thin margin Romney won the county by as Democratic candidate Hillary Clinton lost by nearly 25%, the first time a Republican won by more than 5% in the county since 1924. Trump further increased his margin of victory in 2020 to over 27%, and improved even more in 2024 to nearly a 30% margin of victory.

United States presidential election results for Big Stone County, Minnesota

Year	Republican		Democratic		Third party(ies)
	No.	%	No.	%	No.	%
2024	1,796	63.60%	964	34.14%	64	2.27%
2020	1,863	62.64%	1,053	35.41%	58	1.95%
2016	1,608	58.37%	921	33.43%	226	8.20%
2012	1,385	49.66%	1,345	48.23%	59	2.12%
2008	1,362	45.55%	1,552	51.91%	76	2.54%
2004	1,483	48.35%	1,536	50.08%	48	1.57%
2000	1,370	45.97%	1,430	47.99%	180	6.04%
1996	990	32.99%	1,619	53.95%	392	13.06%
1992	1,052	30.76%	1,610	47.08%	758	22.16%
1988	1,469	41.66%	2,026	57.46%	31	0.88%
1984	1,821	47.34%	1,994	51.83%	32	0.83%
1980	1,950	47.67%	1,814	44.34%	327	7.99%
1976	1,332	33.24%	2,581	64.41%	94	2.35%
1972	1,748	43.52%	2,185	54.39%	84	2.09%
1968	1,645	41.69%	2,119	53.70%	182	4.61%
1964	1,331	31.90%	2,831	67.86%	10	0.24%
1960	1,834	42.83%	2,437	56.91%	11	0.26%
1956	1,737	44.25%	2,180	55.54%	8	0.20%
1952	2,260	51.46%	2,107	47.97%	25	0.57%
1948	1,321	33.99%	2,466	63.46%	99	2.55%
1944	1,608	42.86%	2,120	56.50%	24	0.64%
1940	1,925	42.95%	2,517	56.16%	40	0.89%
1936	1,116	27.91%	2,648	66.22%	235	5.88%
1932	868	20.99%	3,200	77.37%	68	1.64%
1928	1,641	43.20%	2,133	56.15%	25	0.66%
1924	1,524	46.14%	260	7.87%	1,519	45.99%
1920	2,415	78.16%	451	14.60%	224	7.25%
1916	810	44.88%	869	48.14%	126	6.98%
1912	244	14.56%	677	40.39%	755	45.05%
1908	965	57.78%	565	33.83%	140	8.38%
1904	1,234	73.10%	318	18.84%	136	8.06%
1900	1,081	59.27%	644	35.31%	99	5.43%
1896	1,048	55.72%	742	39.45%	91	4.84%
1892	576	41.68%	498	36.03%	308	22.29%

County Board of Commissioners

Position		Name	District
	Commissioner	Chad Zimmel	District 1
	Commissioner	Wade Athey	District 2
	Commissioner and Chairperson	Brent Olson	District 3
	Commissioner	Roger Sandberg	District 4
	Commissioner	Jeff Klages	District 5

State Legislature (2018–2020)

Position		Name	Affiliation	District
	Senate	Torrey Westrom	Republican	District 12
	House of Representatives	Jeff Backer	Republican	District 12A

U.S Congress (2021–2023)

Position		Name	Affiliation	District
	House of Representatives	Michelle Fischbach	Republican	7th
	Senate	Amy Klobuchar	Democrat	N/A
	Senate	Tina Smith	Democrat	N/A

School districts include:

• Chokio-Alberta Public School District
• Clinton-Graceville-Beardsley School District
• Lac Qui Parle Valley School District
• Ortonville Public Schools

• National Register of Historic Places listings in Big Stone County, Minnesota
• List of Minnesota placenames of Native American origin

• Big Stone County website

45°26′N 96°25′W / 45.43°N 96.41°W / 45.43; -96.41