Crazy thing I learned about today: Black Tuesday, 1939 in St. Louis. The coal pollution was so bad that eventually the city was covered in so much smog they had to leave the street lights on during the day. Insane.
"On Tuesday, November 28, 1939, a meteorological temperature inversion trapped emissions from coal burning close to the ground resulting in "the day the sun didn’t shine". A cloud of thick black smoke enveloped St. Louis, far worse than any previously seen in the city. The day came to be known as "Black Tuesday". The smog hung about for 9 days over the course of the following month."