Sandhogs are urban miners and underground construction workers who’ve been tunneling through sand, mud, and bedrock for well over a century. They dug New York’s subway, traffic, sewer, and water tunnels, as well as foundations for structures like the Woolworth Building. The term “sand hogs” originated with workers digging the sandy bottom of the East River inside caissons to build the Brooklyn Bridge. Over time, the term expanded to describe any laborer working underground in the City, and became specifically tied to the Local 147 Sandhogs Union. NYC built three deep pressure tunnels through bedrock to carry water throughout the five boroughs. Placing them hundreds of feet underground kept the water supply safely below any utility and subway tunnels, and the depth required laborers who could work under often grueling and dangerous conditions.