Rattlesnake Bar was a small mining community located at the Placer County and El Dorado County line along the North Fork American River. During 1863 a wooden bridge was constructed at Rattlesnake Bar to facilitate access to quarry at Coral Caverns (now Alabaster Caverns). The original wooden span was replaced in 1865 with a suspension bridge. The 1865 suspension bridge would be open to traffic until 1954 when it was destroyed by an overloaded truck. The site of the Rattlesnake Bar Suspension Bridge became part of the Folsom Lake reservoir in 1955 and can still be viewed when the water is low.
https://www.gribblenation.org/2024/02/rattlesnake-bar-suspension-bridge.html?m=1