Sunbury County was a county in Nova Scotia. The county ceased to exist when the province of New Brunswick was created in 1784.
The county was created in 1765, and included the north and eastern portions of Cumberland County as well as the eastern portion of the District of Maine. The county's seat and its court of general sessions were established at Campobello.
The Province of Massachusetts was jurisdictionally in control of the District of Maine, though in practice, neither Boston nor Halifax were interested in expending energy or money to administer the area so the geographic overlap was permitted to exist.
In 1784, the western third of the county was returned to the District of Maine, which was then part of the U.S. state of Massachusetts. The remainder became the colony of New Brunswick, which was created in part due to the immigration to Nova Scotia of many thousands of Loyalists refugees following the American Revolutionary War.
Today, there is a remnant of the original county which continues the name - Sunbury County is located in central New Brunswick.
Coordinates: 46°0′19.6″N 66°25′16.5″W / 46.005444°N 66.421250°W