The short version of the history is that Chicago was once the hub for a progressivist strain of non-Christian Unitarianism, identified at its peak for its intellectual rigor and argumentative flintiness. Those days are past, and while I would have opposed that movement if I had been born a century earlier, "Western Unitarianism" holds a soft spot in my heart.
So in keeping with the season I present for your consideration a song -- or rather, two songs -- by Sufjan Stevens, who is better known for his works with implicit Christian themes. Make that that songs, with allusions that western Unitarians, their heirs and even Universalists would recognize.
"Come On! Feel the Illinoise! (Part I: The World's Columbian Exposition – Part II: Carl Sandburg Visits Me in a Dream)"