The Gold Country (also known as Mother Lode Country) is a historic region in the northern portion of the U.S. state of California, that is primarily on the western slope of the Sierra Nevada. It is famed for the mineral deposits and gold mines that attracted waves of immigrants, known as the 49ers, during the 1849 California Gold Rush.
When gold was first discovered in 1848 many people came from all over the world to find gold. The migration into California brought diseases and violence.  There were 500 mining camps of which 300 are still undiscovered as of today. There was 400 million dollars in gold mined between 1849 and 1855.  In 1942 most of the mines shut down due to World War II.  The transportation in Gold Country grew rapidly due to the Gold Rush. The first railroad in California ran through Gold Country.  There were 250 different stage coach companies formed by 1860. 
Major Events Per County:
- Amador County – At the time of the Gold Rush the Kennedy Mine was the deepest in the world at 5,919 feet. Argonaut Mine was from 1850 to 1942. In 1922, there was a fire in the area and 47 men were trapped in the mine and died. This mine was shut down due to the war. In Amador County it was such a rural area that they lacked government. Because of the lack of government, the citizens took care of the situations. Many people were hung within a day. 
- Butte County – Cherokee was hydraulic-mined from 1860 to 1870. Cherokee was the first place to find diamond in the United States in 1864. In Oroville was the Chinese temple which was established in 1863. The Chinese worked on the railroads and mining the area. 
- Calaveras County – This county was known for the biggest gold nugget found in the United States. The nugget weighed 195 lb. The nugget was found in Carson Hill. In Copperopolis, $72 million worth of copper was found. Many of the copper mines in this area supplied the Union armies needs in the Civil War. In 1856 Mitchler Hotel was built. Black Bart stayed in this hotel numerous times. 
- El Dorado County – This county is the key to the Gold Country. This is where gold was discovered in 1848 by James Marshall at Sutter's Mill.  Sutter's fort was destroyed by all the people that came here from the Gold Rush. 
- Mariposa County – Located in the southern portion of Hwy 49. This county is known for the Ghirardelli Factory dated all the way back, 1855–1858. One of the mines that were in Mariposa County was the Princetown Mine which, pulled out $5 million in gold. 
- Nevada County – This county had the most gold out of all of Gold County pulled out of it totaling $440 million worth. Holbrooke Hotel is one of the oldest hotels still run to this day in Gold Country. It was built in 1851. Empire Mine one of the most-known mines in the area. (This mine is now a state park.) This mine runs 200 miles underground. This mine was still in operation after the war. One hundred million dollars' worth of gold was mined out of this mine. Nevada County Narrow Gauge Railroad was constructed in 1876. This railroad was made so that people can travel faster between Grass Valley to Nevada City. It was shut down in 1942. In 1851 in North Bloomfield a lot the mines were producing high volumes of gold but died out by 1853. Malakoff Diggings was known for its booming hydraulic mining. 
- Placer County – Colfax was known for a main station for supplies from the Central Pacific Railroad. Many of the area was known for quartz. About $2 million in quartz was found. Placer County was known for the robber "Rattlesnake Dick" in 1850. 
- Plumas County – Gold was first found in this county at Rabbit Creek. 60 million in gold was found in the La Porte area. John Bidwell first discovered gold in the Feather River. Spanish Ranch had over $100 million worth of gold come out of it. In Crescent Mill they found a gold vein 20 feet thick. 
- Sierra County – Allegheny was known for a 163-pound gold nugget. The mine was shut down during the war but then was opened back up in 1965. This mine is still mined occasionally today. In 1992 seventy thousand dollars was mined out of it. In 1849 gold was first found in the Yuba river in Downieville. A 427-pound nugget was found there. Hydraulic mining happened at Howland Flat and Poker Flat in the 1850s. Seven hundred thousand dollars' worth of gold came out of Poker Flat alone. 
- Tuolumne County – In Knights Ferry there was the largest covered bridge on the west coast dating back to 1862. In Jamestown they found a 75-pound golden nugget. Sierra Railroad House was built in 1897. It was a popular site for filming movies. Eagle Shawmut Mine had $7.4 million mined out of it. 
- Yuba County – This county was known for dredging the rivers, mills, hydraulic mining and its many little towns. Most of the towns were built around trails. They provided hotels, stores, and bars for the newcomers. They had one of the largest dredgers ever, in the Yuba River at one point. It dredged 4.8 million ounces of gold.  Black Bart was known in this area for robbing the Wells Fargo stagecoaches coming from La Porte. Colgate Powerhouse went into use for the first time in 1899. It supplied power to Sacramento and Oroville.  One of the most famous towns in Yuba County was Camptonville. Gold was first discovered in this town in 1850. The area under the town was so rich in gold that they moved the town to get to the gold.  Marysville was known for a main place that people brought their gold to be shipped out to San Francisco. Millions of dollars in gold came through Marysville, one of the biggest cities in California at the time. 
The Gold Country lies on the western slope of the Sierra Nevada, reaching down to the Sacramento Valley. The oldest geology can be found along the easternmost portions of this region, closer to the Sierra Nevada summits, which formed 100 million years ago.  It consists of ancient sea floor and portions of islands which were added onto the western edge of North America during the late Paleozoic, about 275 million years ago. The western sections of the Mother Lode are significantly younger, from the mid- Mesozoic about 150 million years ago, and also consist of material that was solidified on the ocean floor to the continental edge. Massive intrusions of granite forced their way into these formations. After ten miles of overlying material was eroded over the last 70 million years, these intrusions became visible throughout the Sierra Nevada. Over the last 50 million years, rivers and volcanoes deposited materials; these built up in thick layers found atop many of the high ridges of the Sierra Nevada foothills.
This part of California has a Mediterranean climate like much of Italy and Spain, making wine grapes and vineyards one of the region's primary crops and industry.[ citation needed] Over 100 wineries are found throughout the Gold Country. Winters are cool and wet with occasional snowfall, especially in the higher elevations of the eastern reaches up the slopes of the Sierra Nevada mountains. Winter temperatures range from the upper twenties to mid-fifties. Summers are dry and hot, with long stretches that reach triple digits. The average annual precipitation is around 30 inches (760 mm). Many dams were built in the Sierra Nevada to hold water. People in California depend on the water that comes from the Sierra Nevada mountains. 
Counties and the towns that are part of Gold Country:
- Amador County
- Butte County
- Calaveras Country
- El Dorado County
- Mariposa County
- Nevada County
- Placer County
- Plumas County
- Sierra County
- Tuolumne County
- Yuba County
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