Sutter's Fort was a 19th-century agricultural and trade colony in the Mexican Alta California province. Established in 1839, the site of the fort was originally called New Helvetia by its builder John Sutter, though construction of the fort proper would not begin until 1841. The fort was the first non-indigenous community in the California Central Valley. The fort is famous for its association with the Donner Party, the California Gold Rush, and the formation of the city of Sacramento, surrounding the fort. It is notable for its proximity to the end of the California Trail and Siskiyou Trails, which it served as a waystation.

New Helvetia, meaning "New Switzerland", was a 19th-century Alta California settlement and rancho, centered in present-day Sacramento, California.