There is a train line that crosses the Delaware River, running along the edges of the Benjamin Franklin Bridge.
On the east bank of the river, eastbound trains descend underground before eventually reemerging and climbing onto elevated tracks that carry commuters through the small towns that dot the increasingly suburban landscape of southern New Jersey.
From one of those small, drowsy towns, those trains can be heard clearly as they pass. The whine of the electric motors and the rush of the passenger cars cutting through the air makes a repetitive, comforting addition to the acoustic rhythm of the place. The train sounds like the town. The town sounds like the train.
High above this town, which lies just a few miles northeast of the Philadelphia International Airport, there is a particularly busy strip of troposphere. The planes flying overhead are sometimes low enough to make their own contribution to the soundscape, with their softer, slower hum.
On clear nights, the methodical blinking lights that announce those planes creep across the dark sky, past the faint stars and the distant Philadelphia skyline.
And on clear days, the afternoon sunlight sometimes reflects so perfectly off of those aircraft that their outline appears carved from the blue of the sky itself. The body of a plane, shimmering in the warm sun and the underside of the wings, a deep black. It pulls a shadow behind it that will cross those train tracks, leave that small town, and float over the river, in want of no bridge.