Detailed Maps (Updated) from Boston's Molasses Flood of 1919 - A brief video

The molasses tank explosion sent steel plates right through the supports of the elevated train on Commercial Ave. 

I've always been fascinated with the Boston Molasses Flood of 1919. It's a true and tragic story of a two million gallon steel tank filled with molasses. Apparently the tank was built in a substandard way, using materials and techniques that were weaker than what was required. The tank basically came apart at the rivets on a 40 degree day in January, 1919. The day before had been only 2 degrees, and some theories say the molasses expanded, stressing the completely full tank. When the tank let go, the pressure turned sheets of steel into projectiles, and then the molasses itself became a giant destructive wave, taking out whole buildings nearby. While there was no chemical "explosion" the result was similar. In an instant, the tank was gone, and shrapnel was everywhere. Check out these photos.

This map overlay shows the location of the tank in 1917. Almost exactly on the first ballfield after to the left of the bocce courts.

The tank was right next to Commercial Street. This was a residential neighborhood in 1919.

[Click the triangle above to start playing the video]

Also: You can try the maps yourself by clicking here: Open Boston Atlas with 1917 Overlay Showing the Molasses Tank

By the way, in those days, there WAS a rail link between North and South station, and this elevated was how that was accomplished. The elevated was taken down in the 1940's, and I remember seeing a photo of the demolition showing a giant billboard next to the project saying "Scrap to beat the Japs". The billboard was from Lipsett Demolition, which really caught my attention, because that's my Aunt Marcia (Lipsett) Warner's (now in her 80's)  father's and uncle's company. That company also took down New York's elevated trains.

Update October 2, 2010:

This, book, Dark Tide by Steven Puleo goes into amazing detail about the disaster. Working off of court records from the lawsuit that ensued, Puleo paints a detailed picture of the people and events that led up to tragedy.

I'm about 1/3 through the book, but it has already revealed some new things I didn't realize. He mentioned at some length that the tank was mainly important to keep USIA's distillery in Cambridge running at peak capacity. They would offload the molasses from ships from Cuba, then put it on rail cars to be be sent to the USIA plant in Cambridge. So I had to find out where this plant was.
I found this listing on Google Books. It's an ad from a 1921 journal for druggists. Purity made industrial alcohol, some of which went for medical use, but as Puleo's book outlines, the big push was to maximize production of alcohol as an ingredient in explosives manufacturing to support the needs of European countries in World War I

Here is the 1916 Bromley Atlas map, from a company called Community Heritage Maps. (Here's the Cambridge overview) They have a wonderful collection of Bromley Atlases which they let you browse, and which they will print in a variety of forms. The 1916 map clearly shows the Purity Distilling Company taking up a few blocks at 943 Cambridge Street.

The 1930 Bromley Atlas shows the Purity Distilling site as mostly vacant.

This overlay shows that the distilling plant was right in the middle of a residential neighborhood, just as the molasses tank in Boston was just feet away from a densely populated North End. Note the round blue tank at the top. Probably a smaller holding tank for alcohol, or maybe molasses. Note on the 1916 map that there are train tracks on the northern side.

Molasses Flood Links:
 Wikipedia Article on the Flood - Note that their map is most certainly wrong. I put in a comment to that effect, with links proving the error. (See last comment on the discussion page.) 
Modern Marvels "Engineering Disasters"- They have an 8-minute segment, which I'll bet is very good. Maybe make a Tivo wish list for "molasses" and it will pick this one up when it plays on the History Channel. (Can anyone find this online for viewing? Add a comment below if you can.)