Lake County is a county located in the U.S. state of Colorado. As of the 2020 census, the population was 7,436. The county seat and the only municipality in the county is Leadville. The highest natural point in Colorado and the entire Rocky Mountains is the summit of Mount Elbert in Lake County at 14,440 feet (4,400 meters) elevation.

Lake County was one of the original 17 counties created by the Colorado legislature on November 1, 1861. As originally defined, Lake County included a large portion of western Colorado to the south and west of its present boundaries. The county was named for Twin Lakes.

Placer gold was found at Colorado Gulch in 1863 as part of the Colorado Gold Rush.

Lake County slowly lost territory over the succeeding decades, losing land in its southeast to Saguache County in 1866 and Hinsdale County in 1874; in its southwest to La Plata County in 1874 and San Juan County in 1876, and in its west to Ouray and Gunnison counties in 1877.

With its many reductions in size, Lake County's designated county seat also changed multiple times within just a few years, residing successively in Oro City (from 1861), Lourette (from 1863), Dayton (from 1866), and Granite (from 1868).

By 1878, Lake County had been reduced to an area including only present-day Lake and Chaffee counties. On February 8, 1879, the Colorado legislature renamed Lake County as Carbonate County, although this designation name only lasted for two days, until Chaffee County was split off from Carbonate's southern section on February 10 and the remaining northern portion was redesignated Lake County with its current county seat of Leadville.

According to the U.S. Census Bureau, the county has a total area of 384 square miles (990 km), of which 377 square miles (980 km) is land and 7.0 square miles (18 km) (1.8%) is water. It is the fourth-smallest county in Colorado by area.

As the courthouse with the highest elevation in the United States, the Lake County courthouse in Leadville is the "highest court" in the land.

• Eagle County – north
• Summit County – northeast
• Park County – east
• Chaffee County – south
• Pitkin County – west

• U.S. Highway 24
• State Highway 82
• State Highway 91

The 2013 horror video game Outlast is set in a fictional asylum in Lake County.

Historical population

Census	Pop.	Note	%±
1870	522		—
1880	23,569		4,415.1%
1890	14,603		−38.0%
1900	18,054		23.6%
1910	10,600		−41.3%
1920	6,630		−37.5%
1930	4,899		−26.1%
1940	6,833		39.5%
1950	8,600		25.9%
1960	7,101		−17.4%
1970	8,318		17.1%
1980	7,491		−9.9%
1990	6,007		−19.8%
2000	7,102		18.2%
2010	7,310		2.9%
2020	7,436		1.7%
2023 (est.)	7,365		−1.0%
U.S. Decennial Census 1790–1960 1900–1990 1990–2000 2010–2020

As of the census of 2000, there were 7,812 people, 2,977 households, and 1,914 families living in the county. The population density was 21 people per square mile (8.1 people/km). There were 3,913 housing units at an average density of 10 units per square mile (3.9 units/km). The racial makeup of the county was 77.60% White, 0.18% Black or African American, 1.25% Native American, 0.31% Asian, 0.05% Pacific Islander, 17.99% from other races, and 2.62% from two or more races. 36.14% of the population were Hispanic or Latino of any race.

There were 2,977 households, out of which 33.90% had children under the age of 18 living with them, 50.70% were married couples living together, 8.40% had a female householder with no husband present, and 35.70% were non-families. 26.30% of all households were made up of individuals, and 5.60% 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 3.15.

In the county, the population was spread out, with 26.90% under the age of 18, 12.80% from 18 to 24, 33.10% from 25 to 44, 20.60% from 45 to 64, and 6.60% who were 65 years of age or older. The median age was 30 years. For every 100 females there were 115.80 males. For every 100 females age 18 and over, there were 116.70 males.

The median income for a household in the county was $37,691, and the median income for a family was $41,652. Males had a median income of $30,977 versus $24,415 for females. The per capita income for the county was $18,524. About 9.50% of families and 12.90% of the population were below the poverty line, including 15.60% of those under age 18 and 6.30% of those age 65 or over.

United States presidential election results for Lake County, Colorado

Year	Republican		Democratic		Third party(ies)
	No.	%	No.	%	No.	%
2020	1,497	37.79%	2,303	58.14%	161	4.06%
2016	1,270	39.70%	1,616	50.52%	313	9.78%
2012	1,098	36.12%	1,839	60.49%	103	3.39%
2008	1,078	35.91%	1,859	61.93%	65	2.17%
2004	1,261	42.76%	1,623	55.04%	65	2.20%
2000	1,056	40.18%	1,296	49.32%	276	10.50%
1996	728	29.71%	1,338	54.61%	384	15.67%
1992	605	20.70%	1,426	48.79%	892	30.52%
1988	969	38.10%	1,516	59.61%	58	2.28%
1984	1,364	49.65%	1,324	48.20%	59	2.15%
1980	1,375	45.45%	1,213	40.10%	437	14.45%
1976	1,575	48.03%	1,549	47.24%	155	4.73%
1972	1,556	53.67%	1,263	43.57%	80	2.76%
1968	1,025	35.50%	1,550	53.69%	312	10.81%
1964	681	22.32%	2,362	77.42%	8	0.26%
1960	954	34.03%	1,842	65.72%	7	0.25%
1956	1,433	51.31%	1,355	48.51%	5	0.18%
1952	1,303	44.98%	1,585	54.71%	9	0.31%
1948	838	33.49%	1,581	63.19%	83	3.32%
1944	1,236	42.08%	1,687	57.44%	14	0.48%
1940	1,403	40.30%	2,063	59.26%	15	0.43%
1936	650	23.03%	2,146	76.02%	27	0.96%
1932	801	34.89%	1,436	62.54%	59	2.57%
1928	990	40.10%	1,449	58.69%	30	1.22%
1924	1,005	43.00%	613	26.23%	719	30.77%
1920	1,287	53.16%	992	40.97%	142	5.87%
1916	993	25.46%	2,672	68.51%	235	6.03%
1912	966	22.92%	1,933	45.87%	1,315	31.21%
1908	1,918	40.08%	2,652	55.41%	216	4.51%
1904	3,026	50.07%	2,936	48.59%	81	1.34%
1900	2,385	32.60%	4,755	65.00%	175	2.39%
1896	255	3.76%	6,518	96.04%	14	0.21%
1892	1,003	30.68%	0	0.00%	2,266	69.32%
1888	2,901	54.01%	2,413	44.93%	57	1.06%
1884	3,416	55.52%	2,661	43.25%	76	1.24%
1880	3,801	46.70%	4,197	51.56%	142	1.74%

Lake County has leaned towards the Democratic Party for most of its history, voting for that party's presidential nominee in every election since 1988.

• Leadville

• Leadville North
• Twin Lakes

• Climax

• Oro City

• Healy House Museum and Dexter Cabin
• Leadville National Historic District

• Arkansas Headwaters Recreation Area

• San Isabel National Forest (part)
  • Buffalo Peaks Wilderness (part)
  • Collegiate Peaks Wilderness (part)
  • Holy Cross Wilderness (part)
  • Mount Massive Wilderness (part)
    • Leadville National Fish Hatchery (part)

• American Discovery Trail
• Colorado Trail
• Continental Divide National Scenic Trail
• Mineral Belt National Recreation Trail

• Top of the Rockies National Scenic Byway

• Bibliography of Colorado
• Geography of Colorado
• History of Colorado
  • National Register of Historic Places listings in Lake County, Colorado
• Index of Colorado-related articles
• List of Colorado-related lists
  • List of counties in Colorado
• Outline of Colorado

• Lake County Government website
• Colorado County Evolution by Don Stanwyck
• Colorado Historical Society
• Lake County Visitor Center

39°11′N 106°22′W / 39.19°N 106.36°W / 39.19; -106.36