Harlan County is a county in the U.S. state of Nebraska. As of the 2020 United States Census, the population was 3,073. Its county seat is Alma. The county is home to the Harlan County Reservoir.

In the Nebraska license plate system, Harlan County is represented by the prefix 51 (it had the 51st-largest number of vehicles registered in the county when the license plate system was established in 1922).

Prior to 1870, the portion of the Republican valley that now includes Harlan County was a prized hunting ground for indigenous peoples, and their efforts to keep intruders away deterred white settlement in the area. The defeat of the Sioux at the Battle of Summit Springs in 1869 largely eliminated this threat, and several parties were organized to explore the agricultural possibilities of the area.

A party of forty men from eastern Nebraska settled near the site of present-day Orleans in August 1870. In 1871, a party from the Wyoming Territory, led by Thomas Harlan, settled near present-day Alma, which was named after a settler's daughter. In that year, Harlan County was separated from Lincoln County by the Nebraska state legislature. Accounts differ as to the county's namesake: either Thomas Harlan, or James Harlan, who was U.S. Secretary of the Interior between 1865 and 1866.

The Republican River flows southeastward across the lower part of Harlan County, being impounded by the Harlan County Lake at the SE corner of the county. The terrain consists of gently rolling low hills, with the majority of flat areas being used for center pivot irrigation.

The county has a total area of 574 square miles (1,490 km), of which 553 square miles (1,430 km) is land and 21 square miles (54 km) (3.6%) is water.

• South East Sacramento State Wildlife Management Area
• South Sacramento State Wildlife Management Area

Historical population

Census	Pop.	Note	%±
1880	6,086		—
1890	8,158		34.0%
1900	9,370		14.9%
1910	9,578		2.2%
1920	9,220		−3.7%
1930	8,951		−2.9%
1940	7,130		−20.3%
1950	7,189		0.8%
1960	5,081		−29.3%
1970	4,357		−14.2%
1980	4,292		−1.5%
1990	3,810		−11.2%
2000	3,786		−0.6%
2010	3,423		−9.6%
2020	3,073		−10.2%
2021 (est.)	3,091		0.6%
US Decennial Census 1790-1960 1900-1990 1990-2000 2010-2013

As of the 2000 United States Census, there were 3,786 people, 1,597 households, and 1,049 families in the county. The population density was 7 people per square mile (2.7 people/km). There were 2,327 housing units at an average density of 4 units per square mile (1.5/km). The racial makeup of the county was 98.86% White, 0.13% Black or African American, 0.11% Native American, 0.08% Asian, 0.03% Pacific Islander, 0.16% from other races, and 0.63% from two or more races. 0.77% of the population were Hispanic or Latino of any race.

There were 1,597 households, out of which 25.70% had children under the age of 18 living with them, 59.00% were married couples living together, 4.30% had a female householder with no husband present, and 34.30% were non-families. 30.80% of all households were made up of individuals, and 16.70% had someone living alone who was 65 years of age or older. The average household size was 2.34 and the average family size was 2.93.

The county population contained 24.20% under the age of 18, 5.00% from 18 to 24, 21.60% from 25 to 44, 26.20% from 45 to 64, and 23.00% who were 65 years of age or older. The median age was 44 years. For every 100 females there were 98.00 males. For every 100 females age 18 and over, there were 96.80 males.

The median income for a household in the county was $30,679, and the median income for a family was $36,875. Males had a median income of $27,580 versus $18,411 for females. The per capita income for the county was $15,618. About 7.00% of families and 10.10% of the population were below the poverty line, including 14.40% of those under age 18 and 9.10% of those age 65 or over.

• Alma (county seat)

• Mascot
• Oxford Junction

Harlan County voters are reliably Republican. In no national election since 1936 has the county selected the Democratic Party candidate.

United States presidential election results for Harlan County, Nebraska

Year	Republican		Democratic		Third party(ies)
	No.	%	No.	%	No.	%
2024	1,506	83.43%	280	15.51%	19	1.05%
2020	1,615	83.51%	282	14.58%	37	1.91%
2016	1,496	81.66%	254	13.86%	82	4.48%
2012	1,395	78.46%	354	19.91%	29	1.63%
2008	1,329	75.25%	402	22.76%	35	1.98%
2004	1,467	77.33%	398	20.98%	32	1.69%
2000	1,358	73.33%	438	23.65%	56	3.02%
1996	1,120	60.28%	520	27.99%	218	11.73%
1992	992	46.88%	488	23.06%	636	30.06%
1988	1,403	65.13%	725	33.66%	26	1.21%
1984	1,692	76.80%	493	22.38%	18	0.82%
1980	1,690	72.94%	486	20.98%	141	6.09%
1976	1,325	58.76%	879	38.98%	51	2.26%
1972	1,549	74.19%	539	25.81%	0	0.00%
1968	1,392	64.03%	579	26.63%	203	9.34%
1964	1,283	51.78%	1,195	48.22%	0	0.00%
1960	1,766	66.42%	893	33.58%	0	0.00%
1956	1,850	68.57%	848	31.43%	0	0.00%
1952	2,300	75.91%	730	24.09%	0	0.00%
1948	1,490	54.98%	1,220	45.02%	0	0.00%
1944	1,991	66.43%	1,006	33.57%	0	0.00%
1940	2,182	61.73%	1,353	38.27%	0	0.00%
1936	1,692	44.36%	2,084	54.64%	38	1.00%
1932	1,272	32.79%	2,486	64.09%	121	3.12%
1928	2,702	69.98%	1,055	27.32%	104	2.69%
1924	1,845	50.01%	1,216	32.96%	628	17.02%
1920	1,756	59.59%	974	33.05%	217	7.36%
1916	834	37.48%	1,267	56.94%	124	5.57%
1912	325	15.78%	918	44.58%	816	39.63%
1908	1,081	44.99%	1,158	48.19%	164	6.82%
1904	1,178	57.77%	299	14.66%	562	27.56%
1900	880	44.74%	977	49.67%	110	5.59%

• National Register of Historic Places listings in Harlan County, Nebraska

• Field Guide to the Geology of the Harlan County Lake Area, Harlan County, Nebraska — with a History of Events Leading to Construction of Harlan County Dam online pdf
• Rogers, Jean McKee. History of Harlan County 1870-1967.

• Harlan County Tourism Office

40°10′N 99°24′W / 40.17°N 99.40°W / 40.17; -99.40