Allegheny River Lock and Dam No. 4 - Credit: Wikimedia Commons
Allegheny River Lock and Dam No. 4 - Credit: Wikimedia Commons
The Allegheny River Lock and Dam No. 4 in Harrison Township, Allegheny County, Pennsylvania, is a lock that was built 1920-1927, and opened in 1927, 24.2 miles upstream from the mouth of the river in Pittsburgh. The lock and dam were built by the U.S. Army Corps of Engineers as a part of an extensive system of locks and dams to improve navigation along the Allegheny River. Read more on Wikipedia
Source: en.wikipedia.org