The following year, the Chicago, Milwaukee & St. Paul Railway, also known as the "Milwaukee Road" continued west, reaching Bristol, South Dakota. In 1881, the line was again extended to Andover, South Dakota; a distance of less than 10 miles.
Because of the massive plateau and the several hundred feet of elevation difference, the Bristol to Andover section took a year to complete. Through this area, the route made a jag to accommodate the elevation loss of nearly 400 feet in just under 10 miles.
In 1881, work continued, reaching Aberdeen by the end of the year. In 1882, the Hastings & Dakota became part of the Milwaukee Road system, after being leased for years.
Further extensions were made from Aberdeen to Ipswich in 1883, Ipswich to Bowdle in 1885 and Bowdle to the Glenham in 1900.
As the railroad made plans to continue further west towards the Pacific Coast, it was decided to cross the Missouri River west of Glenham. The bridge at Mobridge would open in 1906, and the line from Glenham to the North Dakota/Montana border near Marmarth, North Dakota.
Construction continued the following year towards Miles City, Montana, before being opened in early 1908. The railroad continued construction westwards towards Seattle.
The line west of Mobridge was incredibly expensive, dangerous and difficult to construct. In addition, because the conditions posed through Montana were so extreme, it was decided to electrify the route west of Roundup, Montana.
At a cost of over 257 million Dollars (over 7 billion Dollars today), the route was well engineered. Despite this, the massive expense plunged the Milwaukee Road into bankruptcy.
Not long after the Pacific Extension was completed, work began to double track and realign the route between Aberdeen and Minneapolis. The first segments completed included Milbank to Twin Brooks, South Dakota and Bristol to Aberdeen in 1913.
This massive project saw complete realignment of most of the main line between Ortonville and Waubay. Massive amounts of dirt were moved and new bridges were constructed for the state of the art line.
In early 1914, financial issues caused work to cease on the double tracking project, and some areas were determined to be best served by improved single track. By the end of the year, double track line was completed between Milbank and Aberdeen.
With the exception of areas around Ortonville, Minnesota and Big Stone City, South Dakota; the Appleton to Milbank segment was never double tracked. The segment between Andover and Bristol also was never double tracked. The entire route was completed in 1915.
However, the route never saw traffic to justify the double track route. Overly optimistic predictions proved incorrect, and traffic never flourished as expected on the Pacific Extension. As a result, the second track between Bristol and Summit was removed in 1934, Milbank to Twin Brooks in 1953, Andover to Aberdeen in 1953 and Summit to Milbank in 1957.
As the years wore on, the Milwaukee Road found itself in huge financial trouble. As a result, the entire Pacific Extension west of Miles City was abandoned in 1980. The route between Appleton and Miles City was sold to Burlington Northern in 1982.
BN altered the end of the line to Terry in 1982, where it currently ends. In 1996, the Burlington Northern merged with the Atchison, Topeka & Santa Fe to form BNSF, the current owners of the Appleton to Terry route.
Today, the Appleton to Aberdeen segment is known as the Appleton Subdivision, the Aberdeen to Hettinger, North Dakota segment is known as the Mobridge Subdivision, and the Hettinger to Terry segment is now the Hettinger Subdivision.
Located just west of Big Stone City along US-12, this massive concrete arch is the largest arch bridge between Minneapolis and Aberdeen on this route.
Built in 1913-1914 during the line relocation and double tracking to cross the Whetstone River, the bridge features two absolutely massive concrete arch spans. At 60 feet long each, these are also likely the largest arch spans in the State of South Dakota on any railroad.
It was reported in Railway Review, Volume 26 that expansion joints were constructed into this bridge, partially because of the size of the arches, and also because issues with early cracking in other arches along the Milwaukee Road system. While expansion joints are common on roads and bridges today, the author has never seen such a thing in virtually any other concrete arch built for railroad use. An example of such a bridge with cracking in the spandrel walls (above the arch) can be seen near Gladwin, Iowa on the Kansas City line.
Image showing bridge soon after completion. Taken from Railway Review, Volume 26
The process of building this bridge was well documented through photos. Because this area was a lowlands, tons of fill was needed to raise the tracks and build the new alignment. This was accomplished through the use of temporary trestles and work trains. The work trains would then dump soil until the desired height was reached.
Once the fill was completed, the bridge construction began. It appears the footings and the arch rings were one pour, and then the rest of the bridge was done in other pours.
Minnesota Reflections has done a terrific job documenting the construction of this bridge. A photo showing the beginning of construction on the bridge can be seen here, while another photo showing the arches beginning to be formed can be seen here.
The original alignment was significantly lower than the current route, and it crossed the Whetstone River twice; once north of this bridge, and once near the Minnesota border.
Today, the arch is relatively secluded, and is best accessed from a large cliff along US-12. Unfortunately for the bridge, significant stabilization of the arches was needed at some time, leading to the metal bars that now help hold it up.
Overall, the arch appears to be in fair to poor condition. Cracks have begun to form in the arch, and it has needed bracing. The original expansion joints have largely done their job however, and can still be seen in the structure.
The author has ranked this bridge as being regionally significant, due to the large size, unique features and old age.
The photo above is an overview from the cliff along US-12.