It's just after sunset with temperatures close to zero as Amtrak train no. 6, the California Zephyr, wastes no time descending the grade at Coal Creek Canyon during the cold blue hour.
A continuously growing album of photos that IMHO reveal the awesome and seldom-seen beauty of the railroad world from the dimming of day to dawn's early light! From dusk to dawn, trains roll on! (I'm still finding gems of sunset-to-sunrise surprises!)