The
Cincinnati Subway was a partially completed
rapid transit system beneath the streets of
Cincinnati,
Ohio. Although the system only grew to a little over 2 miles (3.2 km) in length, its derelict tunnels and stations make up the largest abandoned subway tunnel system in the
United States. Construction began in the early 1900s as an upgrade to the
Cincinnati streetcar system, but was abandoned due to escalating costs, the collapse of funding amidst political bickering, and the
Great Depression during the 1920s and 1930s.
In 1928, the construction of the subway system in Cincinnati was indefinitely canceled. There are no plans to revive the project.