Johnstown Flood National Memorial

Johnstown, Cambria County, Pennsylvania Listed October 15, 1966 Ref. 66000656 Structure

Why it's listed

Dam remnants and farm buildings in Cambria County, Pennsylvania, make up this park. The South Fork Dam was built by the Commonwealth of Pennsylvania between 1838 and 1853 to supply water to the Western Division of the Pennsylvania Main Line Canal. In 1879 a group of Pittsburgh industrialists formed the South Fork Fishing and Hunting Club and purchased the dam and reservoir, which was renamed Lake Conemaugh, for a summer resort. On May 31, 1889, heavy rains raised the lake beyond safe levels, and the poorly reconstructed dam failed, sending a wall of water down the valley into Johnstown. The disaster caused more than 2,200 deaths and over $17 million in property damage. The park preserves the earthen abutments, the spillway, and the sluice foundation. The Elias J. Unger House, built around the mid-1880s, stands nearby, and it is linked to the disaster through Unger's actions on the morning of the flood.

Significance in brief: The failure of the South Fork Dam on May 31, 1889 caused the most notable and devastating flood of the nineteenth century in the United States, with over 2,200 lives lost and more than $17 million in property damage. The nomination argues the event gave rise to a large body of literature and offers lessons for engineering and environmental management. The Unger House and outbuildings are significant for their link to Elias J. Unger, a club president who was at the property during the flood.

Machine-generated summary. This summary was generated by a language model from the official nomination document and has not been reviewed line by line by an editor. It may contain errors. Check the source document before relying on any detail. Source: nomination document (PDF) · National Archives catalog entry. NRHP reference 66000656, listed October 15, 1966. Summary generated October 2026 (model claude-haiku-5-5, prompt v1.1-2026-10-29, confidence medium).

Key facts

Address	Jct. of U.S. 219 and PA 869, Johnstown
County	Cambria County
Listed	October 15, 1966
Reference number	66000656
Resource type	Structure
Period of significance	1838-1889
Architectural style	Vernacular version of the Gothic Revival style (Unger House)
Criteria	A — associated with events that made a significant contribution to history B — associated with the lives of significant people C — distinctive architecture, design or construction D — has yielded, or may yield, important information (archaeology)
Areas of significance	Other
Level of significance	National
Status (as stated in the nomination)	Dam remains are largely abutments and foundations; the Unger House is stabilized with a temporary roof; the spring house is collapsing; the main barn and carriage shed have collapsed into ruins.
Acreage	163.5
Coordinates	40.34179, -78.77972 (NPS GIS)

What listing means for this property

For a publicly owned building or structure, listing mainly matters when federal funds, permits or licences are involved: projects then go through Section 106 review so effects on the property are considered. Listing also strengthens applications for preservation grants and, for leased income-producing uses, can enable the federal rehabilitation tax credit.

General information, not legal or tax advice. Rules change; confirm with your State Historic Preservation Office or a qualified adviser.

Sources and further reading

National Park Service, National Register of Historic Places database (snapshot May 2026), reference 66000656.
Nomination form (PDF, National Archives) — catalog entry
Wikipedia article (used for cross-checking only; text not reproduced here)
Wikidata Q6268782
This listing as JSON

Last updated October 2026. Found an error? See the editorial policy for how to report it.