Wednesday, May 6, 2020

BNSF/Milw and US-12 Bridges near Mobridge, MO

1907 RR: (Bridge Hunter)
1961 RR: (Bridge Hunter; John A. Weeks IIISatellite)
1924 US-12: (Bridge Hunter)
1959 US-12: (Bridge Hunter; John A. Weeks IIIISatellite)

Chris Yeoman commented on his post (below)

Public Domain via Bridge Hunter

Note the above railroad and road bridges crossed a lot skinnier river than today's bridges cross.

Street View
[The railroad bridge is in the foreground and the US-12 bridge is in the background.]

That is because this location is now part of Lake Oahe, which is the reservoir created by the Oahe Dam.

Chris Yeoman posted
Eastbound grain train at Mobridge SD today crossing the Missouri River / Oahe Reservoir.
[The US-12 bridge is peaking out above the train.]
Edward Davies When the River got wider the railroad decided that they needed Mobridge.
Paul Martig The town was actually named after the bridge, or more precisely for the original railroad designation of the location for the original railroad bridge. The designation was Missouri Bridge, which got shortened to Mobridge. Isn't Wikipedia wonderful?

John Weeks - BNSF
[There is a long embankment in the reservoir on the left.]

Paul Everett photo via Bridge Hunter, License: Creative Commons Attribution-Share-Alike (CC BY-SA)

John Weeks - US-12


I accessed an old topo map to see what the river looked like before the dam was built. I was shocked to discover that the oldest map available, 1953, shows the river to be as wide as it is today. I was shocked because they just started construction in 1952, and it wasn't closed until 1958. And it took four years to fill up enough so that they could start producing hydroelectric power.
1953 McIntosh Quadrangle @ 1:250,000

So I wondered if the cartographer was trying to "future proof" his map. After all, he has all of the contour information needed to predict where the new river banks would be. Indeed, he did anticipate the future because the 1958 map shows the reality of the 1950s.
1958 McIntosh Quadrangle @ 1:250,000

3 photos (There are several interesting comments including more photo.s)

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