The Isthmus Slough Bridge is significant as a good example of the bascule bridge type. This bridge is unique within the Oregon context at it is the only known bascule structure that utilizes a block and tackle lifting mechanism, as opposed to the more common motorized lifting mechanism. The lack of motorized technology distinguishes this structure within Oregon's context of moveable bridges. The Isthmus Slough Bridge is also significant as a late example of the bascule type within Oregon, as it is only one of three bascule spans built after WWII.
(HAER OR-144 - Isthmus Slough Bridge)
Length of largest span: 85.0 ft.
Total length: 686.1 ft.
Deck width: 24.0 ft.
Vertical clearance above deck: 14.1 ft.
Eligible for the National Register of Historic Places
Approximate latitude, longitude
+43.30083, -124.20861(decimal degrees) 43°18'03" N, 124°12'31" W (degrees°minutes'seconds")