Prior to municipal amalgamation in 1995, it was an incorporated town and the shire town of Northumberland County.
Situated on the north bank of the Miramichi River, the former town is sometimes referred to as Miramichi West.
Being a former shire town, Newcastle is the location of several government offices and the county court house. It was an important transportation centre as it was located at the head of navigation on the Miramichi River and had wharves for the export of lumber and other forest products. During the mid-1870s the Intercolonial Railway was built through the town, placing it on the mainline between Halifax and Montreal. The town's most prosperous days are considered to be the years prior to World War I. It later reached a peak population of about 6,500.
- Newcastle, New Brunswick on Wikipedia