Lassen County (/ˈlæsən/ LASS-ən) is a county located in the northeastern portion of the U.S. state of California. As of the 2020 census, the population was 32,730. The county seat and only incorporated city is Susanville. Lassen County comprises the Susanville, California, micropolitan statistical area. A former farming, mining, and lumber area, its economy now depends on employment at one federal and two state prisons; the former in Herlong and the latter two in Susanville. In 2007, half the adults in Susanville worked in one of the facilities.

Lassen County was formed on April 1, 1864, from parts of Plumas and Shasta counties following the two-day conflict known as the Sagebrush War, also called the Roop County War, that started on February 15, 1863. Due to uncertainties over the California border, the area that is now Lassen County was part of the unofficial Nataqua Territory and Roop County, Nevada, during the late 1850s and early 1860s.

The county was named by California after Peter Lassen, along with Lassen Peak, which is in adjoining Shasta County. Lassen was one of General John C. Fremont's guides, and a famous trapper, frontiersman, and Indian fighter. He was murdered under mysterious circumstances near the Black Rock Desert in 1859, and his murder was never solved.

By the 1880s small towns began to spring up all over Lassen County. Bieber developed at the north end of the county, in rich farm land. Gold was discovered at Hayden Hill, and the small town developed to support the miners. Hayden Hill no longer exists: when the mining stopped, the townspeople left for other communities. Madeline was formed at the north end of another rich farming valley, and along the railroad tracks heading north to Alturas, California. This community still has about 50 people living in and around the town. In the 1890s many immigrant family groups arrived in the county, primarily coming from Lincolnshire and Herefordshire, England as well as the towns of Belgrade, Novi Sad, Niš and Kragujevac in Serbia. Several "Yankee" settlers arrived from Waldo County, Maine and Lincoln County, Maine as well.

During World War I, the area was heavily in favor of American entry into the war, and a disproportionate amount of volunteers from Lassen County signed up to take part in the war effort. A pro-German newspaper editor from San Francisco noted that "the inhabitants of Lassen County" were "sympathetic to Britain, hostile to Germany, and indifferent to France."

A narrow gauge railroad, the Nevada-California-Oregon Railway, ran through Lassen County from 1880 to 1927. The NCOR was the longest small gauge of the century. It was intended to connect Reno, Nevada, to the Columbia River, but only 238 miles (383 km) of track were laid, from Reno to Lakeview, Oregon.

In 1913, the Fernley & Lassen Railroad was built and it was used to export timber from the large forests of Lassen County. As this railroad was completed, the Red River Lumber Company set up shop, building the town of Westwood, California, to support its massive logging operation. Two other lumber mills followed the Red River Lumber Co. They built their mills in the county seat of Susanville. The Lassen Lumber and Box Company and the Fruit Growers Company both operated mills in Susanville for several decades.

In 2003, Anderson-based Sierra Pacific Industries announced plans to relocate or lay off 150 workers as they closed the last lumber mill in Susanville due to the lack of large timber for the mill. Sierra Pacific chose to close the mill permanently rather than spend the several million dollars required to convert the mill from large to small timber.

Since the late 20th century, three prisons have been opened in and near Susanville: California Correctional Center (minimum security, 1963) and High Desert State Prison (California) (maximum security, 1995), both in the city; and the nearby Federal Correctional Institution, Herlong (opened 2007). In 2007, half the adults in Susanville worked in one of the three prisons. In "job-starved rural America, ... residents see them [prisons] as the last and only chance for employment after work at the lumber mill or the dairy dries up."

Lassen County is served by Lassen Community College, Lassen High School District, Mt. Lassen Charter School, Thompson Peak Charter School, Diamond Mountain Charter High, Diamond View Middle School, Herlong High School, Meadow View Elementary, McKinley Elementary, Long Valley Charter School, Fort Sage Charter School, and Westwood Junior Senior High School.

According to the U.S. Census Bureau, the county has a total area of 4,720 square miles (12,200 km), of which 4,541 square miles (11,760 km) is land and 179 square miles (460 km) (3.8%) is water. Part of Lassen Volcanic National Park extends onto a western corner of the county.

• Modoc County, California - north
• Washoe County, Nevada - east
• Sierra County, California - southeast
• Plumas County, California - south
• Shasta County, California - west

• Lassen National Forest (part)
• Lassen Volcanic National Park (part)
• Modoc National Forest (part)
• Plumas National Forest (part)
• Toiyabe National Forest (part)

Lassen County, California – Racial and ethnic composition
Note: the US Census treats Hispanic/Latino as an ethnic category. This table excludes Latinos from the racial categories and assigns them to a separate category. Hispanics/Latinos may be of any race.

Race / Ethnicity (NH = Non-Hispanic)	Pop 2000	Pop 2010	Pop 2020	% 2000	% 2010	% 2020
White alone (NH)	23,893	23,270	19,534	70.63%	66.69%	59.68%
Black or African American alone (NH)	2,976	2,790	2,244	8.80%	8.00%	6.86%
Native American or Alaska Native alone (NH)	959	999	939	2.83%	2.86%	2.87%
Asian alone (NH)	244	337	472	0.72%	0.97%	1.44%
Pacific Islander alone (NH)	134	163	283	0.40%	0.47%	0.86%
Other Race alone (NH)	267	363	142	0.79%	1.04%	0.43%
Mixed race or Multiracial (NH)	674	856	1,585	1.99%	2.45%	4.84%
Hispanic or Latino (any race)	4,681	6,117	7,531	13.84%	17.53%	23.01%
Total	33,828	34,895	32,730	100.00%	100.00%	100.00%

Population, race, and income
Total population	35,001
White	24,515	70.0%
Black or African American	3,048	8.7%
American Indian or Alaska Native	1,300	3.7%
Asian	464	1.3%
Native Hawaiian or other Pacific Islander	162	0.5%
Some other race	4,467	12.8%
Two or more races	1,045	3.0%
Hispanic or Latino (of any race)	6,075	17.4%
Per capita income	$19,339
Median household income	$52,484
Median family income	$65,396

Places by population and race
Place	Type	Population	White	Other	Asian	Black or African American	Native American	Hispanic or Latino (of any race)
Bieber	CDP	280	82.5%	16.1%	1.4%	0.0%	0.0%	16.1%
Clear Creek	CDP	138	96.4%	3.6%	0.0%	0.0%	0.0%	15.2%
Doyle	CDP	367	96.5%	3.5%	0.0%	0.0%	0.0%	0.8%
Herlong	CDP	1,260	32.0%	38.5%	1.0%	24.4%	4.1%	47.0%
Janesville	CDP	1,302	92.8%	1.2%	6.0%	0.0%	0.0%	2.5%
Johnstonville	CDP	656	97.0%	0.9%	0.0%	0.0%	2.1%	5.6%
Litchfield	CDP	95	100.0%	0.0%	0.0%	0.0%	0.0%	0.0%
Milford	CDP	99	100.0%	0.0%	0.0%	0.0%	0.0%	0.0%
Nubieber	CDP	38	92.1%	7.9%	0.0%	0.0%	0.0%	7.9%
Patton Village	CDP	624	58.0%	9.6%	0.0%	19.2%	13.1%	8.0%
Spaulding	CDP	137	94.9%	0.0%	0.0%	0.0%	5.1%	0.0%
Susanville	City	17,728	65.0%	17.3%	1.5%	10.7%	5.5%	19.9%
Westwood	CDP	1,473	92.7%	2.9%	0.6%	0.1%	3.7%	2.6%

Places by population and income
Place	Type	Population	Per capita income	Median household income	Median family income
Bieber	CDP	280	$25,141	$61,250	$54,844
Clear Creek	CDP	138	$29,639	$44,167	$60,313
Doyle	CDP	367	$23,339	$27,917	$32,885
Herlong	CDP	1,260	$5,943	$43,958	$45,893
Janesville	CDP	1,302	$25,821	$71,090	$70,481
Johnstonville	CDP	656	$31,534	$60,682	$67,813
Litchfield	CDP	95	$37,227	$41,528	$45,556
Milford	CDP	99	$38,215	$61,472
Nubieber	CDP	38	$9,524	$31,250	$31,563
Patton Village	CDP	624	$27,081	$46,447	$62,656
Spaulding	CDP	137	$30,669	$35,714	$51,806
Susanville	City	17,728	$16,580	$49,160	$68,780
Westwood	CDP	1,473	$23,055	$38,512	$51,215

Historical population

Census	Pop.	Note	%±
1870	1,327		—
1880	3,340		151.7%
1890	4,239		26.9%
1900	4,511		6.4%
1910	4,802		6.5%
1920	8,507		77.2%
1930	12,589		48.0%
1940	14,479		15.0%
1950	18,474		27.6%
1960	13,597		−26.4%
1970	14,960		10.0%
1980	21,661		44.8%
1990	27,598		27.4%
2000	33,828		22.6%
2010	34,895		3.2%
2020	32,730		−6.2%
2023 (est.)	28,861		−11.8%
U.S. Decennial Census 1790–1960 1900–1990 1990–2000 2010–2015

The 2010 United States Census reported that Lassen County had a population of 34,895. The racial makeup of Lassen County was 25,532 (73.2%) White, 2,834 (8.1%) African American, 1,234 (3.5%) Native American, 356 (1.0%) Asian, 165 (0.5%) Pacific Islander, 3,562 (10.2%) from other races, and 1,212 (3.5%) from two or more races. Hispanic or Latino of any race were 6,117 persons (17.5%).

Population reported at 2010 United States Census
The County	Total Population	White	African American	Native American	Asian	Pacific Islander	other races	two or more races	Hispanic or Latino (of any race)
Lassen County	34,895	25,532	2,834	1,234	356	165	3,562	1,212	6,117
Incorporated city	Total Population	White	African American	Native American	Asian	Pacific Islander	other races	two or more races	Hispanic or Latino (of any race)
Susanville	17,947	11,269	2,249	612	198	111	2,928	580	4,259
Census-designated place	Total Population	White	African American	Native American	Asian	Pacific Islander	other races	two or more races	Hispanic or Latino (of any race)
Bieber	312	264	0	15	1	0	24	8	72
Clear Creek	169	149	0	5	0	2	1	12	15
Doyle	678	583	14	37	3	2	12	27	55
Herlong	298	187	38	16	1	3	9	44	46
Janesville	1,408	1,283	13	32	11	3	27	39	118
Johnstonville	1,024	929	7	16	13	0	26	33	73
Litchfield	195	176	0	0	0	0	14	5	25
Milford	167	150	1	1	1	1	4	9	11
Nubieber	50	26	0	13	0	0	6	5	10
Patton Village	702	552	48	27	4	5	18	48	62
Spaulding	178	168	0	3	1	0	1	5	6
Westwood	1,647	1,430	3	104	10	2	49	49	179
Other unincorporated areas	Total Population	White	African American	Native American	Asian	Pacific Islander	other races	two or more races	Hispanic or Latino (of any race)
All others not CDPs (combined)	10,120	8,366	461	353	113	36	443	348	1,186

As of the census of 2000, there were 33,828 people, 9,625 households, and 6,776 families residing in the county. The population density was 7 people per square mile (2.7 people/km). There were 12,000 housing units at an average density of 3 per square mile (1.2/km). The racial makeup of the county was 80.8% White, 8.8% Black or African American, 3.3% Native American, 0.7% Asian, 0.4% Pacific Islander, 3.2% from other races, and 2.7% from two or more races. 13.8% of the population were Hispanic or Latino of any race. 13.8% were of German, 12.1% Irish, 10.5% English, 8.7% American and 5.0% Italian ancestry according to Census 2000. 88.2% spoke English and 10.3% Spanish as their first language.

There were 9,625 households, out of which 35.9% had children under the age of 18 living with them, 55.8% were married couples living together, 10.3% had a female householder with no husband present, and 29.6% were non-families. Of all households, 24.5% were made up of individuals, and 9.2% had someone living alone who was 65 years of age or older. The average household size was 2.59 and the average family size was 3.08.

In the county, the population was spread out, with 21.8% under the age of 18, 10.8% from 18 to 24, 36.9% from 25 to 44, 21.4% from 45 to 64, and 9.0% who were 65 years of age or older. The median age was 35 years. For every 100 females there were 168.8 males. For every 100 females age 18 and over, there were 192.2 males.

The median income for a household in the county was $36,310, and the median income for a family was $43,398. Males had a median income of $37,333 versus $26,561 for females. The per capita income for the county was $14,749. About 11.1% of families and 14.0% of the population were below the poverty line, including 16.1% of those under age 18 and 7.8% of those age 65 or over.

Population and registered voters
Total population	35,001
Registered voters	13,932	39.8%
Democratic	3,401	24.4%
Republican	6,687	48.0%
Democratic–Republican spread	-3,286	-23.6%
Independent	726	5.2%
Green	43	0.3%
Libertarian	95	0.7%
Peace and Freedom	37	0.3%
Americans Elect	1	0.0%
Other	67	0.5%
No party preference	2,875	20.6%

Cities by population and voter registration
City	Population	Registered voters	Democratic	Republican	D–R spread	Other	No party preference
Susanville	17,728	25.2%	26.7%	44.1%	-17.4%	12.5%	22.0%

From 1932 through 1976, Lassen was powerfully Democratic, voting for the Democratic presidential nominee in every election save 1972, when it voted for Nixon over McGovern by just 6.8%. From 1980 on, however, it has been overwhelmingly Republican in presidential and congressional elections, coinciding with the dominance of the prisons in local employment. Jimmy Carter (in 1976) remains the last Democrat to have carried the county. In both 2016 and 2020, Lassen stood as Donald Trump's best county in the state, giving him a 50% or greater margin over overwhelming statewide winners Hillary Clinton and Joe Biden.

United States presidential election results for Lassen County, California

Year	Republican		Democratic		Third party(ies)
	No.	%	No.	%	No.	%
2020	8,970	74.47%	2,799	23.24%	276	2.29%
2016	7,574	70.79%	2,224	20.79%	901	8.42%
2012	7,296	68.03%	3,053	28.47%	376	3.51%
2008	7,483	65.45%	3,586	31.37%	364	3.18%
2004	8,126	70.97%	3,158	27.58%	166	1.45%
2000	7,080	66.88%	2,982	28.17%	524	4.95%
1996	5,194	52.60%	3,318	33.60%	1,363	13.80%
1992	3,836	37.02%	3,388	32.70%	3,138	30.28%
1988	5,157	58.59%	3,446	39.15%	199	2.26%
1984	5,352	61.09%	3,254	37.14%	155	1.77%
1980	4,464	54.45%	2,941	35.87%	793	9.67%
1976	3,007	42.97%	3,801	54.32%	190	2.72%
1972	3,618	50.80%	3,134	44.00%	370	5.20%
1968	2,553	41.06%	2,930	47.12%	735	11.82%
1964	2,124	34.25%	4,072	65.67%	5	0.08%
1960	2,365	40.24%	3,472	59.08%	40	0.68%
1956	2,533	42.48%	3,412	57.22%	18	0.30%
1952	3,313	43.66%	4,237	55.83%	39	0.51%
1948	1,960	33.95%	3,632	62.91%	181	3.14%
1944	1,896	33.92%	3,678	65.81%	15	0.27%
1940	1,902	30.13%	4,367	69.17%	44	0.70%
1936	1,035	19.62%	4,193	79.47%	48	0.91%
1932	1,167	26.89%	3,056	70.41%	117	2.70%
1928	2,111	56.73%	1,597	42.92%	13	0.35%
1924	1,072	40.78%	356	13.54%	1,201	45.68%
1920	1,582	66.22%	643	26.92%	164	6.86%
1916	877	36.96%	1,323	55.75%	173	7.29%
1912	27	1.91%	644	45.61%	741	52.48%
1908	551	54.61%	361	35.78%	97	9.61%
1904	573	62.69%	301	32.93%	40	4.38%
1900	549	58.10%	326	34.50%	70	7.41%
1896	420	43.66%	528	54.89%	14	1.46%
1892	540	48.09%	524	46.66%	59	5.25%

Lassen County is in California's 1st congressional district, represented by Republican Doug LaMalfa. is in the 1st Senate District, represented by Republican Brian Dahle, and the 1st Assembly District, represented by Republican Megan Dahle.

The following table includes the number of incidents reported and the rate per 1,000 persons for each type of offense.

Population and crime rates
Population	35,001
Violent crime	96	2.74
Homicide	1	0.03
Forcible rape	6	0.17
Robbery	9	0.26
Aggravated assault	80	2.29
Property crime	196	5.60
Burglary	101	2.89
Larceny-theft	229	6.54
Motor vehicle theft	25	0.71
Arson	11	0.31

Cities by population and crime rates
City	Population	Violent crimes	Violent crime rate per 1,000 persons	Property crimes	Property crime rate per 1,000 persons
Susanville	17,849	96	5.38	320	17.93

Susanville Municipal Airport, Herlong Airport and Westwood Airport are general aviation airports in the county. The closest major airport is in Reno.

• U.S. Route 395
• State Route 36
• State Route 44
• State Route 139
• State Route 299

Lassen Rural Bus (LRB), operated by the Lassen Transit Service Agency, runs a local service in Susanville, with longer distance routes to Westwood and Doyle.

The Lassen Municipal Utility District (LMUD) is the primary electric utility in the county, and was created in 1986 by purchasing transmission facilities from CP National (now Pacificorp) at a cost of $19 million. In 2019 it had 42 employees, and the General Manager was Doug C. Smith. It is powered in part by the Honey Lake biomass power plant, which runs on wood waste from the nearby Lassen National Forest. The Whaleback Fire caused a significant outage in 2018.

• Susanville (county seat)

• Ravendale
• Standish
• Termo
• Wendel

The population ranking of the following table is based on the 2020 census of Lassen County.

† county seat

Rank	City/Town/etc.	Municipal type	Population (2020 Census)
1	† Susanville	City	16,728
2	Janesville	CDP	2,461
3	Westwood	CDP	1,541
4	Johnstonville	CDP	973
5	Patton Village	CDP	632
6	Susanville Indian Rancheria	AIAN	570
7	Doyle	CDP	536
8	Bieber	CDP	266
9	Herlong	CDP	237
10	Spaulding	CDP	206
11	Clear Creek	CDP	175
12	Litchfield	CDP	160
13	Milford	CDP	147
14	Stones Landing	CDP	86
15	Little Valley	CDP	84
16	Madeline	CDP	21
17	Nubieber	CDP	19

• National Register of Historic Places listings in Lassen County, California

• Official website
• Lassen County Times newspaper
• Lassen County History and Culture