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The Johnstown Flood (also known as the Great Flood of 1889) occurred on 31 May 1889, when the South Fork Dam failed after several days of hard rain.  The South Fork Dam was located 14 m (23 km) upstream of Johnstown, Pennsylvania, USA.  When the damn burst, 20 million tons (18.1 million cubic meters) of water obliterated the towns of South Fork, Mineral Point and East Conemaugh before reaching Johnstown.  2, 209 people were killed, and the flood caused US $17 million in damages.  The Johnstown Flood was the first major disaster handled by the American Red Cross.  Eighteen foreign countries assisted the US with disaster relief.  This was the largest US flood disaster of the 19th century.

History of Johnstown and the South Fork Dam

Swiss immigrant Joseph Johns founded Johnstown in 1855; by 1889, Johnstown had a population of 30,000, mostly Welsh and German immigrants.  Johnstown was known for its steel industry.

Several factors made the Johnstown area vulnerable to flooding.  Johnstown is located at the confluence of the Stony Creek and Little Conemaugh Rivers, where they meet to form the Conemaugh River.  Due to Johnstown’s location in the Conemaugh Valley of the Allegheny range, early development occurred close to the riverbanks and artificially narrowed the river.  For four miles outside of Johnstown, the Conemaugh River runs through what is considered the deepest river gorge east of the Rockies.

The South Fork Dam was constructed between 1838 and 1853 by the Commonwealth of Pennsylvania as part of a scheme to build a canal system in the area.  The canal scheme was abandoned with the advancement of railroads and a group of speculators led by Henry Clay Frisk purchased the disused reservoir in order to build a lakeside resort.

Frisk and his cohorts made several changes to the South Fork Dam, which may have weakened it.  These alterations included lowering the top of the dam to make it wide enough for a road; putting a fish screen in the spillway, which trapped debris; and lowering the lake’s level. 

Lake Conenaugh, as it was called, was elevated 450 ft (137 m) above Johnstown.  It was 2 m (3 km) long and about 1 m (1.6km) wide.  Lake Conemaugh was 60 ft (18 m) deep near the dam and had a perimeter of 7m (11 km).  At its highest point, Lake Conemaugh covered 400 acres (1.6 km2).  The South Fork Dam was 72 ft (22m) high and 931 ft (284 m) long. 

The South Fork Fishing and Hunting Club was opened in 1881.  Between 1881 and 1889, the dam sprang frequent leaks and had to be patched several times, mostly with mud and straw.

The Great Flood of 1889

On 28 May 1889, a storm formed over Nebraska and Kansas, then moved east.  When it struck Johnstown two days later, it went on record as the worst downpour ever recorded in the region; the US Army Signal Corps estimated that 6-10 in (150-250 mm) of rain fell over a 24 hour period.  The rainfall washed away telegraph lines and railroad tracks and filled Lake Conemaugh to bursting.

On the morning of 31 May, Elias Unger, a farmer who lived on a hill above the South Fork Dam, saw what was about to happen.  He enlisted groups of men who attempted to save the dam by clearing the spillway of debris, digging a second  emergency spillway, and battening the eroding structure with mud and rocks.  Meanwhile, downstream in Johnstown, water from the cresting rivers was already filling the streets, rising to heights of up to ten feet.

The South Fork Dam burst at about 15:10 on 31 May 1889.  It took forty minutes for Lake Conemaugh to drain.

The 20 million tons of rushing water hit the small town of South Fork first.  20-30 houses were washed away, but only four were killed, because South Fork was on high ground and most of the residents were able to escape on foot. 

The water rushed downstream where it encountered the 78 ft (24m) high Conemaugh Viaduct.   Debris carried by the surge jammed against the viaduct’s stone arch, and the flood was stopped temporarily; however, when it again broke loose and surged on, it had gained momentum.  The tiny town of Mineral Point, located 1 m (1.6 km) below the viaduct was entirely obliterated when the surge struck it.  30 families lived in Mineral Point; 16 of its residents perished in the flood.

The surge then proceeded downstream to a third village, East Conemaugh.  Train engineer John Hess heard the roar of the approaching water and warned residents by tying down his train whistle and riding backwards ahead of the wave.  Thanks to his efforts many escaped to high ground, but 50 died in East Conemaugh, including 25 passengers on trains in the town.  Hess himself and his locomotive were caught in the flood surge, but Hess survived.

The flood surge hit Johnstown 57 minutes after the South Fork Dam burst.  The wall of water bore down on Johnstown at 40 m (64 km) an hour, at a height of 60 ft (18 m).  When the flood surge struck the Stone Bridge, debris in the water again formed a temporary dam.  The surge then traveled back upstream along the Stoney Creek River, before gravity sent it rushing back towards Johnstown, where it struck a second time, from another direction. 

The debris piled against the Stone Bridge caught on fire, killing 80.  This heap of debris covered 30 acres (12 ha) and reached a height of 70 ft (22m).  Fire raged in the debris for three days afterwards.  Three months and dynamite were needed to remove the pile of debris, due to quantities of steel wire from the ironworks which bound it together.


The Johnstown Flood left 2,209 people dead.  99 whole families died, including 396 children.  124 women and 198 men lost their spouses; 98 children lost both parents.  777 victims were never identified; they were interred in the Plot of the Unknown in Grandview Cemetery in Southmont.

Workmen needed seven days and nights to replace the Conemaugh Viaduct.  1,600 homes were demolished; US $17 million in property damage occurred; four square miles (10 km2) of central Johnstown were destroyed.  Clean-up operations continued for years.

Pennsylvania Railroad restored service to Pittsburgh by 2 June, and provisions began to arrive in Johnstown.  The first call for help requested coffins and undertakers.  Demolitionist "Dynamite Bill" Flinn and his crew cleared the debris at Stone Bridge.  A total of 7,000 relief workers arrived to assist in the aftermath; one of the first was Clara Barton, a nurse and president of the American Red Cross.  She arrived on 5 June 1889 and stayed for five months.  Donations, totaling US $3,742,818.78, poured in from around the US and from eighteen foreign countries including France, Russia, Turkey, and Great Britain. 

The South Fork Fishing and Hunting Club were accused of failing to properly maintain the dam, but they were successfully defended in court by the firm of Knox and Reed (now Reed Smith LLP).  The court ruled the flood was an Act of God and awarded no compensation to the survivors.  Public outcry over this led to many states’ adoption of Rylands vs. Fletcher, a British common law precedent that states that a non-negligent defendant can be held responsible for damages caused by unnatural use of the land.  This ushered in the American legal system’s acceptance, in the 20th century, of strict liability.

Remnants of the South Fork Dam are on display at the  Johnstown Flood National Memorial, built in 1964. 

An eternal flame now burns at Point Park in Johnstown, at the confluence of the Stony Creek and Little Conemaugh Rivers, in memory of the victims of the Johnstown Flood.


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