I am a fan of landscaping State Street, and taking out some lanes because it doesnt carry as much traffic through downtown.
But, I dont think its a good idea to put tall landscaping or trees down State Street, because there is a really nice sight line to the Capitol
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State Street is also plays a huge part in the parades in Salt Lake. So im not sure I like idea of a landscaped middle.
As a side note, I came across this picture of the SLC Valley, kinda cool
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