Petaluma historian Katherine Rinehart provides this background about the Trestle:
Constructed in 1922, the trestle served as a spur line of the Petaluma & Santa Rosa Railroad which handled freight only. The spur linked to the P&SR’s main line at approximately Payran Street, ran south and crossed Washington Street, ran behind the warehouses lining Water Street to Western Avenue, and ran across the trestle behind the Great Petaluma Mill. After the trestle, the spur continued south on First Street and terminated at what we know today as Foundry Wharf.
The passenger depot was at the corner of Copeland and East Washington (it was later moved to the Weller Street). From there the trolley headed up Copeland and crossed the NWP line and continued east to Two Rock and Sebastopol and north to Santa Rosa.
No longer used for rail traffic, the trestle has and will be in the future a promenade and viewing platform for those taking in the annual lighted boat parade, Petaluma Beer Festival and other river related activities.