"The Johnstown Flood (or Great Flood of 1889 as it became known locally) occurred on May 31, 1889. It was the result of the catastrophic failure of the South Fork Dam situated on the Little Conemaugh River 14 miles (23 km) upstream of the town of Johnstown, Pennsylvania, USA, made worse by several days of extremely heavy rainfall. The dam's failure unleashed a torrent of 20 million tons of water (4.8 billion U.S. gallons; 18.2 million cubic meters; 18.2 billion litres) from the reservoir known as Lake Conemaugh. With a volumetric flow rate that temporarily equalled that of the Mississippi River,[2] the flood killed 2,209 people[3] and caused US$17 million of damage (the equivalent of about $425 million in 2012 dollars)." - Wikipedia.
Those are the facts and figures. In
The Johnstown Flood, David McCullough gives you all that and way more.
Behind the numbers and stats, and even the human tragedy, there is an evil lurking here. Perhaps this horrific catastrophe need not have happened if not for a "let them eat cake" attitude by an elite few who wanted to maintain their "Summer camp" pleasure palaces on a dammed lake perched precariously above a small town in a narrow valley below.

The book on the whole reads like a newspaper feature article or Op-Ed piece that comes out a few weeks after a contentious event where more questions than answers arise after the dust settles. It posits questions, hypotheticals, wondering aloud all the what-ifs the public has been asking.
These days your average joe would be hard pressed to give correct details on the Johnstown Flood. The event is fading into memory as time passes and more severe tragedies occur. McCullough, who excels at these history snippets (See, this and his [b:1776|1067|1776|David McCullough|https://d.gr-assets.com/books/1306787560s/1067.jpg|3364186] for proof. I highly recommend both,) does an excellent job of recreating the scene, dredging up the past and hosing it off to look, smell, sound and feel as fresh and as horrid as the day it happened.