Johnstown Flood National Memorial
Why it's listed
Remnants of the South Fork Dam lie in a wooded valley in Cambria County, Pennsylvania. The Commonwealth of Pennsylvania built the earthen and rock-fill dam between 1838 and 1853 to supply water to the Western Division of the Pennsylvania Main Line Canal between Johnstown and Pittsburgh. The Pennsylvania Railroad left the dam largely unattended after 1857, and in 1879 a group of Pittsburgh industrialists formed the South Fork Fishing and Hunting Club, which bought the dam and reservoir and repaired it by 1881. On May 31, 1889, after heavy rains, the poorly reconstructed dam failed, releasing a wall of water that killed more than 2,200 people and caused over $17 million in property damage. The surviving abutments, spillway and sluice foundations show how the dam was built and operated. The Elias J. Unger House, constructed in the mid-1880s, is linked to the disaster because Unger, the club's president, was at the site and tried to lower the water level before the collapse.
Significance in brief: The nomination argues that the 1889 failure of the South Fork Dam caused the most notable and devastating flood of the nineteenth century in the United States and the greatest national catastrophe of the post-Civil War era. The dam itself is significant as a canal water-supply reservoir and recreational lake, and the Unger House is linked to the events of the flood through Elias J. Unger's role at the site.
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). NRHP reference 100010579, listed July 26, 2024. Summary generated October 2026 (model claude-haiku-5-5, prompt v1.1-2026-10-29, confidence high).
Key facts
| Address | 733 Lake Road, Adams |
|---|---|
| County | Cambria County |
| Listed | July 26, 2024 |
| Reference number | 100010579 |
| Resource type | District |
| Period of significance | 1838-1889 |
| Architect / builder | Commonwealth of Pennsylvania; South Fork Hunting and Fishing Club of Pittsburgh (reconstruction in early 1880) |
| Architectural style | Vernacular Gothic Revival (Unger House) |
| Criteria |
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| Areas of significance | Social History |
| Level of significance | National |
| Status (as stated in the nomination) | The South Fork Dam is reduced to its north and south abutments, spillway and foundation remnants; the Unger House was unoccupied for about ten years before 1981, is stabilized with a temporary roof, and the spring house and barns are collapsed or in poor condition. |
| Acreage | 164 |
| Coordinates | 40.34328, -78.77607 (NPS GIS) |
What listing means for this property
This is a historic district. Buildings within its boundary are either contributing (they add to the district's significance) or non-contributing. Owners of contributing income-producing buildings can claim the 20% federal rehabilitation tax credit; homeowners should look at state credits. National Register districts impose no design review by themselves; a local historic district ordinance, if one exists, does (the difference explained).
Noted as vacant in the nomination. Nomination documents can be decades old; current status may differ. If you are considering buying an empty listed property, read the due-diligence checklist.
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 100010579.
- Nomination form (PDF, National Archives)
- This listing as JSON
Last updated October 2026. Found an error? See the editorial policy for how to report it.