Notes:

• The postcard says "Suspension Bridge. Jefferson, S.D." The bridge pictured here may be a predecessor to the current pipeline suspension bridge at Ponca, Nebraska, eight miles west of Jefferson. Patrick S. O'Donnell visited this area in 2006 to photograph the Ponca bridge, but could not locate a pipeline bridge matching the postcard.
• In late 2006, Pete Rissell writes that one of the piers from this pipeline bridge is still visible in the middle of the Missouri River: "In the early 1970s I visited the Ponca State Park and noticed a single concrete bridge support in the middle of the Missouri River. I always thought it was strange because there were no abandoned road or rail right-of-ways in that location... I'm sure that this concrete support matches the one in the foreground shown on your website's postcard labeled "Suspension Bridge, Jefferson SD". My guess is that the current Ponca Pipeline bridge (photographed in 2006) is the replacement because the former suspension bridge had to be relocated due to river flooding. The old concrete support is located approximately 1 mile up-river (to the northwest) from the current pipeline bridge." This pier is visible in satellite imagery at the location provided with this inventory entry.
• In 2009, Dale Harkness writes: "I grew up on a farm only a few miles from the existing pipeline. I believe you are correct that the cement pier does belong to the original gas pipeline. My aunt told me that my grandfather was present while the bridge was being constructed. From my understanding, my grandfather had been filming the construction and almost photographed an unusual event where one of the piers crashed down to the ground after a failed attempt to raise it using a pivot." Dale also provided photos of the construction of the newer bridge in 1961.
• The replacement span appears to have been demolished in late 2006 or 2007.
• Replaced by 1961 (pipeline bridge) - Jefferson vicinity, South Dakota and Ponca State Park, Nebraska, USA.