Personal favorite, the US Gypsum line out of Plaster City, CA. While it does have a standard gauge
line to serve the plant it works as an island. SP Owens Valley NG was similar, yes some was shipped out at Owenyo, much was shipped North to Laws, much an island operation. There is the line
that serves the power plant West of Farmington, total island and standard gauge. There has been
several US lines that were islands, Jackass and Western which ran for just under ten miles out on
the Mercury Nuke site, the current China Lake line, the not that lomg ago used narrow gauge line
on Oahu which ran from the Scofield Barricks to the wharf for munitions loading. I believe the
Seal Beach Naval Weapons Station line served the wharf after the SP connection was severed.