It looks like a painful bruise, which is exactly what it is.
The blow came decades ago, when the industries that drove the Monongahela Valley's growth ground to a halt, taking local economies down with them.
This is what's left, An Lewis said, gesturing to the map above her: a long string of blight, clotted along former steel towns but spreading fast, a cancer of empty homes and lost tax revenue.
And if local governments don't do something, she said, it will get worse.
"We really can't afford to continue the status quo," said Ms. Lewis, executive director of the Steel Valley Council of Governments. "We have to start thinking about something new. These properties are eating away at our communities."
Ms. Lewis' call to action came during a summit on blight held Thursday evening by local government associations -- the Steel Valley COG, the Turtle Creek Valley COG and the Twin Rivers COG -- whose communities have been hit hard by neglect.
The meeting followed the release of a blight study commissioned by the three COGs, which estimated vacant and neglected properties cost the Mon Valley $19.4 million every year in municipal services and lost tax revenue.
The 41 member communities have lost more than $200 million in property value to blight, the report concluded.
"This is an issue that really cuts across the entire county," Allegheny County Executive Rich Fitzgerald said in the summit's opening address. "We know the problems. We know the impact they have on not just the properties that are there, but the properties that surround them."
Police and fire calls account for most of the blight bill, with troubled properties generating $6.4 million annually in police costs and $2.4 million for fire departments. Code enforcement, upkeep by municipalities and property demolitions add another $1.9 million.
But the largest impacts are indirect. A house unfortunate enough to have a wreck for a neighbor loses between 15 and 17 percent of its own value, the report concluded. And about 28,000 properties, worth a combined $1.5 billion, sit within 150 feet of a blighted house in the Mon Valley.
Economic development is a challenge in the Mon Valley, where the roster of departed industries -- U.S. Steel, Westinghouse Electric and Union Switch and Signal, among others -- is far longer than that of the newcomers. The valley has lost 90,000 people, with former steel communities such as Braddock, Clairton and Rankin seeing their populations shrink by as much as two-thirds.
Braddock has the highest vacancy rate among the communities surveyed, with one out of four homes standing empty.
But in four communities, the report saw new opportunity. Churchill, Edgewood, Monroeville and Plum all have high enough property values to make building new homes economically viable. If the municipalities bulldozed blighted homes and built on vacant lots, they could spur a modest building boom that would employ 1,100 workers and generate $118 million in new construction.
The new homes could mean $3.5 million in annual tax revenue, the report concluded.
The study was conducted by the Delta Development Group, a Mechanicsburg consulting firm. It was paid through funding from foundations and the state Department of Community and Economic Development, along with matching funds from the three COGs.
At times, Thursday's summit turned into a group therapy session, with local officials sharing stories and strategies for combating decline -- or complaining about the county.
Paging through the report, Betty Esper said researchers wouldn't even have to leave Homestead to collect their findings.
"I have one code enforcement officer," she said. "I need 10."
Andrew McGill: email@example.com or 412-263-1497.