The city famous for deep dish pizza is in a deep freeze along with the rest of the Midwest. See the Chicago River partly frozen over by the polar vortex.

It gets dyed green every year for St, Patrick's Day but this doesn't happen very often. Back in 2013, the Chicago Tribune wondered what it would take for the Chicago River to freeze. The landmark river is unique in that Lake Michigan flows into it, not vice versa. A huge engineering project at the end of the 1800's reversed the flow of the river to solve a threatening sewage problem. So, considering the volume and temperature of Lake Michigan which feeds into the Chicago River, the entire thing icing over is unlikely and rarely happens. Back to 2012, a meteorologist told the Trib, "it would take a very long period of sustained temperatures of lower than 40 degrees Fahrenheit for the river to begin to freeze."

Now we're seeing it happen. How unparalleled is this? The video below was shot by BBC News in England.