The Great Floods: The Susquehanna Always Wins

Living beside the Susquehanna River has always meant accepting a basic fact: the river will eventually come for you. Harrisburg has learned this repeatedly, and never quite stopped learning it.

In March of nineteen thirty-six, the combination of a warm rain falling on a deep winter snowpack sent the Susquehanna to a height that had not been recorded in two hundred years of observation. The official high water mark at Harrisburg reached twenty-nine point two three feet, more than six feet above the level that defines a major flood. Downtown Harrisburg was submerged. Water reached second-story windows in parts of the city. City Island disappeared entirely under the river's surface. That record stood for thirty-six years.

In June of nineteen seventy-two, Tropical Storm Agnes tracked inland from the Gulf Coast, stalled over Pennsylvania, and released extraordinary amounts of rain across the entire Susquehanna watershed. In Harrisburg, some buildings stood under thirteen feet of water. The Governor's Mansion was flooded on its first floor. The Patriot-News, the city's main newspaper, canceled publication for the first time since it began in eighteen fifty-two. Across Pennsylvania, Agnes destroyed more than three thousand businesses and sixty-eight thousand homes. Fifty people died.

The flood wall system that protects parts of Harrisburg today was expanded significantly after nineteen thirty-six. Agnes proved it was still insufficient.

Those two events together explain something visible about Harrisburg's geography: why certain streets sit oddly elevated, why some riverfront blocks are green space rather than buildings, and why the Walnut Street Bridge is now a pedestrian walkway rather than a road. The river wrote those decisions.