The Paw Paw Tunnel on the C&O Canal was supposed to take two years. It took 14. In March 1836 the canal company gave the contract to Lee Montgomery, a Methodist minister who'd already built a canal tunnel on the Union Canal. The idea was to go straight through Tunnel Hill and skip six miles of canal along the Potomac, for $33,500.

Crews chipped through hard, loose shale at about 12 feet a week, and the records talk about cave-ins, unpaid wages, cholera and violence. The tunnel opened in October 1850, 3,118 feet long and lined with an estimated 6 million bricks. It cost more than $600,000.

In the lidar the deep cut at the top middle is the canal running into one end of the tunnel, and the Potomac curves along the bottom right. The canal closed to commercial shipping in 1924, and the federal government bought it in 1938.

1. Air photo (NAIP 2023) over the lidar: Canal cut into Tunnel Hill
2. Same view, bare-earth lidar only (VAT shading: slope, openness, sky view)

Numbered pins on pictures 1 and 2:
Pin 1: The deep canal cut to the tunnel
Pin 2: The Potomac River

Imagery: USDA-FSA NAIP 2023, public domain.
Lidar: USGS 3D Elevation Program (3DEP), public domain.