to allow clearance of some bridges it must pass under. References External links Historic American Engineering Record (HAER) No. PA-217, "Coraopolis Bridge" Image at HAER. report HAER "Corapolis Bridge, Spanning Ohio River back channel at Ferree Street & Grand Avenue, Corapolis, Allegheny County, PA" 21 pages Text of 21 page HAER writeup at pghbridges.com (this text is in the public domain since it is taken from the Library of Congress HAER report). report HAER "Three Sisters Bridges, Spanning Allegheny River at Sixth, Seventh & Ninth Streets, Pittsburgh, Allegheny County, PA" 43 pages. Text of 43 page HAER writeup at pghbridges.com (this text is in the public domain since it is taken from the Library of Congress HAER report). article at pghbridges.com Google Maps Composite image zoomed in, showing replacement bridge. Bridges completed in 1892 Bridges completed in 1927 Girder bridges in the United States Road bridges on the National Register of Historic Places in Pennsylvania Railroad bridges on the National Register of Historic Places in Pennsylvania Bridges over the Ohio River Road-rail bridges in the United States Bridges in Allegheny County, Pennsylvania Former toll bridges in Pennsylvania National Register of Historic Places in Allegheny County, Pennsylvania Steel bridges in the United States Tied arch bridges in the United States Pratt truss bridges in the United States