For many decades, one of the places to watch trains in southern California was Colton Tower, alongside Colton Crossing, where the Southern Pacific Railroad's "Sunset Route" crossed the Santa Fe Railway's Third District (with also carried Union Pacific trains as well). This four-diamond crossing saw the passage of over 110 trains per day at one time. Eventually, the tower was demolished and then the high volume of rail traffic necessitated the Union Pacific (which had acquired the Southern Pacific) to build an elevated structure over the BNSF Railway's track (BNSF being the new railroad created when the Santa Fe merged with the Burlington Northern). Even Slover Mountain (aka Mount Slover or Marble Mountain), visible to the left to Colton Tower, is now officially listed as a "former mountain," as it has been removed and is now a container storage facility. Since then, this is not the photogenic location it formerly was when a Southern Pacific "caboose hop", with trio of SP U25Bs (led by SP 6715) headed east over the crossing, creating the usual loud clatter in the process. (Colton, California – December 26, 1972)