Hyde County is a county in the U.S. state of South Dakota. As of the 2020 census, the population was 1,262, making it the second-least populous county in South Dakota. Its county seat is Highmore. The county was founded in 1873, as a county of the Dakota Territory, and organized in 1883. It was named for James Hyde, a member of legislature in the 1870s.

Hyde County was created by the territorial legislature on January 8, 1873, with area partitioned from Buffalo County. It was not organized by that action. Its boundaries were altered by changes in October 1879 and February 1883. On November 5, 1883, the county organization was filled and the county was placed in independent operation.

The current Hyde County courthouse was constructed in 1911 (it is currently listed on the National Register of Historic Places). The county organization included a jail until 1974, when the jail was abandoned and jail-related services were contracted to surrounding counties.

The county terrain consists of semi-arid rolling hills, partly devoted to agriculture. The Missouri River flows southeastward at its SW corner, and delineates a portion of the county's south boundary line.

The terrain slopes toward the county's SW corner. Its highest point is on the lower part of its eastern boundary line, at 2,080 ft (630 m) ASL.

Hyde County has a total area of 866 square miles (2,240 km), of which 861 square miles (2,230 km) is land and 5.6 square miles (15 km) (0.6%) is water.

• U.S. Highway 14
• South Dakota Highway 26
• South Dakota Highway 34
• South Dakota Highway 47

• Faulk County - north
• Hand County - east
• Buffalo County - south
• Lyman County - southwest
• Hughes County - southwest
• Sully County - west
• Potter County - northwest

• Chapelle State Game Production Area
• Highmore State Game Production Area
• Rezac Lake State Game Production Area
• Rice Lake State Game Production Area

• Baloun Lake
• Chapelle Lake
• Lake Boehm
• Rezac Lake
• Rice Lake
• Thomas Lake

Historical population

Census	Pop.	Note	%±
1890	1,860		—
1900	1,492		−19.8%
1910	3,307		121.6%
1920	3,315		0.2%
1930	3,690		11.3%
1940	3,113		−15.6%
1950	2,811		−9.7%
1960	2,602		−7.4%
1970	2,515		−3.3%
1980	2,069		−17.7%
1990	1,696		−18.0%
2000	1,671		−1.5%
2010	1,420		−15.0%
2020	1,262		−11.1%
2023 (est.)	1,186		−6.0%
U.S. Decennial Census 1790-1960 1900-1990 1990-2000 2010-2020

As of the 2020 census, there were 1,262 people, 522 households, and 355 families residing in the county. The population density was 1.5 inhabitants per square mile (0.58/km). There were 626 housing units.

As of the 2010 census, there were 1,420 people, 600 households, and 385 families in the county. The population density was 1.7 inhabitants per square mile (0.66/km). There were 708 housing units at an average density of 0.8 units per square mile (0.31 units/km). The racial makeup of the county was 89.1% white, 8.5% American Indian, 0.2% Asian, 0.1% Pacific islander, 0.1% black or African American, 0.2% from other races, and 1.9% from two or more races. Those of Hispanic or Latino origin made up 1.1% of the population. In terms of ancestry,

Of the 600 households, 26.2% had children under the age of 18 living with them, 53.7% were married couples living together, 5.5% had a female householder with no husband present, 35.8% were non-families, and 33.0% of all households were made up of individuals. The average household size was 2.30 and the average family size was 2.92. The median age was 46.4 years.

The median income for a household in the county was $41,196 and the median income for a family was $61,161. Males had a median income of $36,053 versus $28,456 for females. The per capita income for the county was $22,995. About 8.3% of families and 11.2% of the population were below the poverty line, including 11.6% of those under age 18 and 14.1% of those age 65 or over.

• Highmore (county seat)

• Stephan

• Central Hyde
• Crow Creek
• North Hyde

Hyde County voters have been reliably Republican ever since South Dakota's statehood. In only two national elections – the Democratic landslides of Franklin D. Roosevelt in 1932 and Lyndon B. Johnson in 1964 – has the county ever voted for a Democratic presidential candidate – although in the Republican landslides of 1956 (due to a major drought and resultant agricultural problems) and 1972 (due to a strong “favorite son” vote for George McGovern) the county actually voted about 4 points more Democratic than the nation at-large.

United States presidential election results for Hyde County, South Dakota

Year	Republican		Democratic		Third party(ies)
	No.	%	No.	%	No.	%
2024	530	76.26%	148	21.29%	17	2.45%
2020	564	79.44%	136	19.15%	10	1.41%
2016	543	78.70%	125	18.12%	22	3.19%
2012	531	72.44%	189	25.78%	13	1.77%
2008	547	69.68%	226	28.79%	12	1.53%
2004	631	70.11%	259	28.78%	10	1.11%
2000	592	70.90%	218	26.11%	25	2.99%
1996	493	54.54%	309	34.18%	102	11.28%
1992	440	46.07%	301	31.52%	214	22.41%
1988	546	53.58%	436	42.79%	37	3.63%
1984	797	69.43%	350	30.49%	1	0.09%
1980	864	70.76%	273	22.36%	84	6.88%
1976	687	54.39%	572	45.29%	4	0.32%
1972	789	59.50%	533	40.20%	4	0.30%
1968	713	53.81%	499	37.66%	113	8.53%
1964	666	47.50%	736	52.50%	0	0.00%
1960	773	53.94%	660	46.06%	0	0.00%
1956	755	55.84%	597	44.16%	0	0.00%
1952	1,051	72.78%	393	27.22%	0	0.00%
1948	817	59.25%	553	40.10%	9	0.65%
1944	842	64.97%	454	35.03%	0	0.00%
1940	1,018	60.31%	670	39.69%	0	0.00%
1936	795	52.51%	683	45.11%	36	2.38%
1932	678	42.48%	895	56.08%	23	1.44%
1928	961	60.82%	608	38.48%	11	0.70%
1924	669	50.53%	257	19.41%	398	30.06%
1920	710	68.53%	233	22.49%	93	8.98%
1916	438	55.58%	305	38.71%	45	5.71%
1912	0	0.00%	232	33.14%	468	66.86%
1908	455	64.45%	212	30.03%	39	5.52%
1904	443	76.91%	91	15.80%	42	7.29%
1900	286	69.76%	115	28.05%	9	2.20%
1896	223	64.45%	121	34.97%	2	0.58%
1892	184	56.44%	51	15.64%	91	27.91%

• National Register of Historic Places listings in Hyde County, South Dakota

• Official website