Were the Union Pacific Big Blows were banned from Los Angeles the same way steam locomotives were banned from New York.
I doubt it. The Big Blows were retired a few years before the National Environmental Policy Act was enacted. They did occasionally run on the LA&SL line but their primary service was between Cheyenne and Ogden.
My understanding was that a few of the little blows (4500HP) were run in LA, notably the one converted to propane, but the big blows (8500HP) were exclusively run between Cheyenne and Ogden.
Just a very minor point: Steam locomotives were only barred from the borough of Manhattan.
Regular turbine operations with the 8500HP examples into LA were brief, occuring in1962, the hot desert temps derated performance and acclerated mechanical wear, servicing them upon arrival was another matter as experienced shop personal had to be dispatched from Salt Lake which proved cost prohibited.
Dave