"French Settlers originally established the community of French Bar along the Tuolumne River in 1850. After the destructive floods of 1851-52, citizens of French Bar relocated one mile up stream above the flood plain."
"Renamed La Grange, the new town prospered as a mining and agricultural community, and served as the county seat of Stanislaus County from 1856 to 1862"
La Grange lost the county seat to Knights Ferry in 1860, an event which ended the great prosperity of the town. It's population was diminished, but La Grange outlived most Gold Rush towns as a center of hydraulic mining, and later gold dredging. Some of the largest dredges ever built worked the ground in this area.
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La Grange was about 30 miles from my house and I spent a LOT of time there doing research. If I wanted to get out of the house for a while but didn't have a lot of time, I'd head to La Grange. What's cool about it is there's been very little growth in the area, so there's tons of historical structures that weren't knocked in the name of progress. Matter of fact, the Hammond and Bates store pictured at the link is still standing and still operating as the town's only store.