On January 15, 1919, 2.3 million gallons of molasses swept through the streets of Boston after a storage tank burst open, wreaking significant destruction and casualties. The scale of the tragedy has since been attributed at least in part to the unique fluid dynamics of molasses. The molasses was initially able to move very quickly due to its warmer state (estimates at the time claimed it moved at 35 miles per hour, which has since been supported by lab tests on how the incident might have occurred), but as it met the cold January air, it cooled rapidly, making it thicker and heavier. Sadly, a total of 21 people were killed between the initial incident and succumbing to injuries, with another 150 injured. The recovery and cleanup took weeks, during which time workers covered in molasses would trek home every day, so that the sticky substance would eventually reach just about every corner of the city. Boston Harbor was brown through the summer, and for years afterwards Bostonians would claim that on a warm day the smell of molasses still lingered over the city.