Otter Tail County is a county in the U.S. state of Minnesota. As of the 2020 census, its population was 60,081. Its county seat is Fergus Falls. Otter Tail County comprises the Fergus Falls micropolitan statistical area. With 1,048 lakes in its borders, Otter Tail County has more lakes than any other county in the United States.

Native Americans used the area for hunting and fishing, and had permanent dwelling sites. Two Native American tribes were in constant conflict. The Dakota (Sioux) were being pushed from their home area by the Ojibwa (Chippewa) during the late 18th and early 19th centuries. Burial mounds and artifacts can still be found. Some of the oldest Native American remains were found near Pelican Rapids, Minnesota. The remains, nicknamed Minnesota Girl, were dated at about 11,000 BC.

The first European men to enter the county were French and British fur traders. Efforts were made to set up trading posts on the Leaf Lakes and Otter Tail Lake. In the late 19th century, most of the towns were built along the railroad lines. Lumber and agriculture were the major industries in the county at that time. The pine and hardwood forests, transportation system, and markets were instrumental in the development of Fergus Falls into a lumber center. The Wisconsin Territory was established by the federal government effective July 3, 1836, and existed until its eastern portion was granted statehood (as Wisconsin) in 1848. The federal government set up the Minnesota Territory effective March 3, 1849. The newly organized territorial legislature created nine counties across the territory in October of that year. One of those original counties, Dakota, had a section partitioned off in 1851 to create Cass County. On March 18, 1858, the outgoing territorial legislature created Otter Tail County from areas partitioned from Cass and Pembina, another of the original counties created in 1849. The county was named for Otter Tail Lake and the Otter Tail River. The county was not organized in 1858, nor was a county seat specified. On September 12, 1868, the legislature completed the county organization, and specified Otter Tail City as county seat.

Otter Tail City began as a waystation on a fur-trade route between Saint Paul and the Red River valley. The settlement was of sufficient size that when the Minnesota Territory established a US land office for this part of the territory, the office was sited at Otter Tail City. Thus, the city was named as the seat when the county was organized, but people had begun settling the future Fergus Falls area in 1857, and it grew sufficiently that in fall 1872, the vote was taken to move the county seat there. The Northern Pacific Railroad had initially planned to run a line through Otter Tail City, but complications caused the line to be placed in Fergus Falls, which precipitated the county seat move. The Soo Line later made plans to run a line through Otter Tail City, but when townspeople could not agree on the routing, another route east of the city was constructed. Thus, a new city plat was generated, with the settlement name changing to Ottertail.

In 1870, the population of the county was about 2,000. At that time, the principal languages spoken in the county were Norwegian, Swedish, German, and English. By 1875 there was also a sizeable Polish community.

The people of Fergus Falls organized a new county named Holcomb. In 1872, a legislative act abolished Holcomb County, added additional townships to the west, and established Fergus Falls as Otter Tail County's seat.

The Fergus Falls Telephone Exchange Company organized on March 20, 1882, and was in a room at the First National Bank at the corner of Cascade and Lincoln. The system install was very crude. Efforts were made to have telephones installed in the courthouse but commissioners did not feel it was necessary. Eventually a telephone was installed in the auditor's office through a combination of private and public funds. A clerk in the office was tasked with tracking down the officer who was called. The business was sold to the Northwestern Telephone Exchange Company in 1883.

The Otter Tail River flows south and west through the central and western parts of the county on its way to form the Red River in Wilkin County. It is joined by the south-flowing Pelican River west of Fergus Falls. The Leaf River rises in the county and flows east to its confluence with the Crow Wing River in neighboring Wadena County. The Redeye River flows southeast through the county's northeast section toward its confluence with the Leaf in Wadena. The county terrain consists of rolling hills, heavily wooded through its center section, dotted with lakes and ponds, and carved with drainages and gullies. The available area is devoted to agriculture. The county terrain slopes to the west and south. The highest points on the county terrain are at two different locations: Inspiration Peak, at 1,727 ft (526 m), and Pekan Peak (unofficial name) a summit northeast of the village of Urbank in Folden Township, Section 32, at 1,800 ft (550 m) above sea level. The county has an area of 2,225 square miles (5,760 km), of which 1,972 square miles (5,110 km) are land and 252 square miles (650 km) (11%) are covered by water. Otter Tail is one of 17 Minnesota savanna region counties with more savanna soils than either forest or prairie soils. According to its website, the county contains over 1,000 lakes.

Historical population

Census	Pop.	Note	%±
1860	240		—
1870	1,968		720.0%
1880	18,675		848.9%
1890	34,232		83.3%
1900	45,375		32.6%
1910	46,036		1.5%
1920	50,818		10.4%
1930	51,006		0.4%
1940	53,192		4.3%
1950	51,320		−3.5%
1960	48,960		−4.6%
1970	46,097		−5.8%
1980	51,937		12.7%
1990	50,714		−2.4%
2000	57,159		12.7%
2010	57,303		0.3%
2020	60,081		4.8%
2023 (est.)	60,626		0.9%
U.S. Decennial Census 1790-1960 1900-1990 1990-2000 2010-2020

Otter Tail County Racial Composition

Race	Num.	Perc.
White (NH)	54,362	90.5%
Black or African American (NH)	843	1.4%
Native American (NH)	284	0.5%
Asian (NH)	334	0.6%
Pacific Islander (NH)	17	0.03%
Other/Mixed (NH)	2,025	3.4%
Hispanic or Latino	2,216	3.7%

As of the census of 2000, there were 57,159 people, 22,671 households, and 15,779 families in the county. The population density was 29.0 per square mile (11.2/km). There were 33,862 housing units at an average density of 17.2 per square mile (6.6/km). The racial makeup of the county was 97.11% White, 0.29% African American, 0.51% Native American, 0.44% Asian, 0.05% Pacific Islander, 0.84% from other races, and 0.78% from two or more races. Hispanic or Latino of any race were 1.67% of the population. 35.5% were of German and 31.2% Norwegian ancestry.

There were 22,671 households, out of which 30.3% had children under the age of 18 living with them, 60.1% were married couples living together, 6.1% had a female householder with no husband present, and 30.4% were non-families. 26.6% of all households were made up of individuals, and 13.30% had someone living alone who was 65 years of age or older. The average household size was 2.46 and the average family size was 2.98.

The county population contained 24.9% under the age of 18, 7.2% from 18 to 24, 24.2% from 25 to 44, 24.7% from 45 to 64, and 19.0% who were 65 years of age or older. The median age was 41 years. For every 100 females there were 100.4 males. For every 100 females age 18 and over, there were 97.8 males.

The median income for a household in the county was $35,395, and the median income for a family was $42,740. Males had a median income of $30,151 versus $20,930 for females. The per capita income for the county was $18,014. About 6.7% of families and 10.1% of the population were below the poverty line, including 12.1% of those under age 18 and 11.1% of those age 65 or over.

United States presidential election results for Otter Tail County, Minnesota

Year	Republican		Democratic		Third party(ies)
	No.	%	No.	%	No.	%
2020	23,800	65.39%	11,958	32.85%	641	1.76%
2016	20,939	64.43%	9,340	28.74%	2,221	6.83%
2012	18,860	59.55%	12,165	38.41%	645	2.04%
2008	18,077	55.30%	13,856	42.39%	754	2.31%
2004	19,734	61.33%	12,038	37.41%	406	1.26%
2000	16,963	59.50%	9,844	34.53%	1,704	5.98%
1996	11,808	45.68%	10,519	40.69%	3,523	13.63%
1992	11,074	41.52%	9,176	34.41%	6,420	24.07%
1988	14,015	56.96%	10,373	42.16%	216	0.88%
1984	15,664	61.30%	9,714	38.02%	173	0.68%
1980	15,091	57.74%	9,108	34.85%	1,939	7.42%
1976	12,113	49.42%	11,881	48.47%	516	2.11%
1972	13,519	62.21%	7,881	36.27%	331	1.52%
1968	12,483	60.30%	7,400	35.75%	818	3.95%
1964	10,542	51.26%	9,997	48.61%	26	0.13%
1960	13,747	62.94%	8,054	36.87%	42	0.19%
1956	12,764	65.88%	6,571	33.91%	40	0.21%
1952	16,447	75.03%	5,388	24.58%	86	0.39%
1948	11,131	61.25%	6,546	36.02%	495	2.72%
1944	12,351	67.55%	5,823	31.85%	110	0.60%
1940	13,737	63.51%	7,705	35.62%	187	0.86%
1936	8,899	49.14%	8,642	47.72%	569	3.14%
1932	7,416	43.72%	8,805	51.90%	743	4.38%
1928	11,624	68.28%	4,990	29.31%	411	2.41%
1924	7,557	55.45%	568	4.17%	5,504	40.38%
1920	11,084	78.50%	1,741	12.33%	1,294	9.16%
1916	4,328	54.33%	2,858	35.88%	780	9.79%
1912	755	11.53%	1,739	26.57%	4,052	61.90%
1908	3,964	58.07%	2,320	33.99%	542	7.94%
1904	4,642	73.69%	869	13.80%	788	12.51%
1900	3,446	47.19%	3,257	44.60%	600	8.22%
1896	3,544	42.73%	4,482	54.04%	268	3.23%
1892	2,140	37.40%	1,642	28.70%	1,940	33.90%

Otter Tail is a Republican stronghold in U.S. presidential elections, having voted for the party's candidates in every election since 1936. The only Democrats to win the county since Minnesota became a state in 1858 have been Franklin D. Roosevelt in his first election victory, and unsuccessful candidate William Jennings Bryan in 1896.

During the Great Depression, there was a communist faction within the county. The areas where the movement was centered are quite desolate today, but in mid-1932 over 900 people were involved in one of the state's communist organizations at what was a historic low point for farmers. The members of the communist party were very active in the New York Mills area of Newton, Leaf Lake, Blowers, Deer Creek and Paddock Townships. They held meetings, recruited members, placed candidates on local and state tickets, and distributed propaganda. They held dances in Heinola, Menahga, and Sebeka where the Soviet hammer and sickle was proudly displayed and ran a summer camp on East Leaf Lake.

By the time Franklin Roosevelt implemented his New Deal programs in the county, the communist movement began to lose steam. In addition, the Winter War in Europe between Finland and the U.S.S.R. soured many Finnish immigrants on communism (Finns had been a large proportion of the local communists). Carl Peltoniemi, a former local communist, said, "The communist movement within the Finnish community basically ended at the start of the Winter War in 1939–1940."

In the Minnesota House of Representatives, Otter Tail County is divided into two districts, 8A and 8B. They are represented by Republicans Bud Nornes (8A) and Mary Franson (8B). Districts 8A and 8B make up Minnesota State Senate district 8, which is represented by Republican State Senator Bill Ingebrigtsen.

School districts include:

• National Register of Historic Places listings in Otter Tail County, Minnesota

• Otter Tail Country Tourism Association
• Otter Tail County, Minnesota official government’s website
• Otter Tail County Historical Society

46°25′N 95°43′W / 46.41°N 95.71°W / 46.41; -95.71