Just last week, I returned to my hometown of Johnstown, Pennsylvania,  on the 117th anniversary of the great Johnstown Flood of 1889. The tragedy killed 2,209 people on May 31 that year, about one-tenth of the town's population. That the anniversary of the flood falls around Memorial Day adds poignancy to annual ceremonies marking the disaster. This year, I visited the Johnstown Flood National Memorial  and joined a park ranger on a hike across what was once Lake Conemaugh, the recreational lake sited in the hills 14 miles above Johnstown.

In 1889, Lake Conemaugh was owned by the South Fork Fishing and Hunting Club and frequented by elite captains of industry of Pittsburgh: Carnegie, Mellon, Frick. When torrential rains overtopped the earthen dam on May 31, 1889, the dam(whose integrity had been compromised by actions of club managers and previous owners) collapsed, sending 20 million gallons of water racing toward Johnstown  and area towns below. The amount of water that destroyed Johnstown has been estimated as equal in volume to the flow over Niagara Falls for 36 minutes.

The lake bed is now filled with shrubs and trees, and South Fork Creek flows uninhibited through the landscape. Looming overhead are two 70-foot high embankments flanking either side of the valley—all that remains of the failed earthen dam. Each year, 2,209 luminaria are placed near the dam site to remember those who were lost. People gather on Memorial Day at the Plot of the Unknowns in a local cemetery, where 777 unidentified flood victims are interred.

This year, on that hot, sunny and dry day, our little hiking group consisted of a dozen visitors, including many locals. However, I'd venture that most people in the Johnstown area seldom think about their history and the long-ago events that occurred there.

Just a few miles away is another historic site, on other hallowed ground. In Shanksville, Pennsylvania, our generation is creating another memorial for a disaster  burned into our national psyche. How and why do we remember? How will the New Orleans tragedy be dissected by historians and remembered in later years?

That history has yet to be written.

A flash flood WARNING means a flash flood is occurring or will occur very soon. ... Related Red Cross Preparedness Information ... Information Resources: American Red Cross Flash Flood Fact Sheet  Information on surviving floods. Know what to expect. Be prepared ...