Right of way Exeter NH

Just north of Rt 101 in Exeter NH there is an old right of way that runs parallel and just west of the current mainline. The old right of way splits from the mainline just north of 101 and rejoins the current mainline right at the switch at CPF 258. It's very easy to see on google earth or bing maps.

Any ideas when the mainline was moved and why?

As far as I can tell looking at old photo (circa 1951), the current mainline was installed before 1951

http://www.historicaerials.com/aerials. ... &year=1951

looking at historical topo maps it appears the allignment changed between 1893 and 1916.

http://historical.mytopo.com/getImage.a ... g&state=NH
and
http://historical.mytopo.com/getImage.a ... g&state=NH


You can clearly see the Oxbow curve in the river at the bottom of the map.

The river itself appears to have cut through the oxbow in the same time period.