Map - Calaveras County, California (Calaveras County)

Calaveras County, officially the County of Calaveras, is a county in both the Gold Country and High Sierra regions of the U.S. state of California. As of the 2010 census, the population was 45,292. The county seat is San Andreas. Angels Camp is the county's only incorporated city. Calaveras is Spanish for "skulls"; the county was reportedly named for the remains of Native Americans discovered by the Spanish explorer Captain Gabriel Moraga.

Calaveras Big Trees State Park, a preserve of giant sequoia trees, is in the county several miles east of the town of Arnold on State Highway 4. Credit for the discovery of giant sequoias there is given to Augustus T. Dowd, a trapper who made the discovery in 1852 while tracking a bear. When the bark from the "Discovery Tree" was removed and taken on tour around the world, the trees became a worldwide sensation and one of the county's first tourist attractions. The uncommon gold telluride mineral calaverite was discovered in the county in 1861 and is named for it.

Mark Twain set his story "The Celebrated Jumping Frog of Calaveras County" in the county. The county hosts an annual fair and Jumping Frog Jubilee, featuring a frog-jumping contest, to celebrate the association with Twain's story. Each year's winner is commemorated with a brass plaque mounted in the sidewalk of downtown Historic Angels Camp and this feature is known as the Frog Hop of Fame.

In 2015, Calaveras County had the highest rate of suicide deaths in the United States, with 49.1 per 100,000 people.

The Spanish word calaveras means "skulls." The county takes its name from the Calaveras River; it was said to have been named by Spanish explorer Gabriel Moraga, during his 1806–1808 expeditions, when he found many skulls of Native Americans along the banks of the stream. He believed they had either died of famine or been killed in tribal conflicts over hunting and fishing grounds. A more likely cause was a European epidemic disease, acquired from interacting with other tribes near the Missions on the coast. The Stanislaus River, which forms the southern boundary, is named for Estanislao, a Lakisamni Yokuts who escaped from Mission San Jose in the late 1830s. He is reported to have raised a small group of men with crude weapons, hiding in the foothills when the Mexicans attacked. The natives were quickly decimated by Mexican gunfire.

In 1836, John Marsh, Jose Noriega, and a party of men went exploring in Northern California. They made camp along a river bed in the evening, and upon waking discovered that they had camped amid a great quantity of skulls and bones. They also gave the river the name Calaveras. Twain spent 88 days in the county in 1865, during which he heard the story that became "The Celebrated Jumping Frog of Calaveras County" at the Angel Hotel. This story kicked off his career and put Calaveras County on the map.