The Nashua branch as seen in their local ad.
Dunder Mifflin Nashua is a branch of the Dunder Mifflin Paper Company that is based out of Nashua, New Hampshire.
Thus far, the only mention of the Nashua branch on the show was in the episode Local Ad when Michael is shown the Nashua branch's local commercial.
Little else is known about this branch of the Dunder Mifflin Paper Company. In the deleted scenes of Branch Wars however, Michael lists a specific characteristic of each branch, explaining that Nashua has "no parking."
Staff
Regional Manager of the Nashua Branch
There are no known staff members of the Nashua branch, however the branch's regional manager can be seen fairly clearly in the local commercial.
In the episode, Survivor Man, Toby mentions that a man named Mark Chisholm attended Ryan's wilderness retreat, indicating that Chisholm is a regional manager. It is possible that he is the regional manager of the Nashua branch, though he could be the regional manager for Akron, Camden, or Yonkers.