Ganong considers the name to have "probably" come from Westmorland's proximity to Cumberland in England, or by the marshes in the English county.[10]
Westmorland County was part of Cumberland County, Nova Scotia until New Brunswick was created, and Westmorland Parish was part of the Nova Scotia township of Cumberland.[11]
Cumberland Township was organised in Nova Scotia in 1763.[12]
Westmorland was erected as a parish in 1786[13] from the New Brunswick portion of Cumberland Township. The exact boundary with Nova Scotia was not finalised until 1862.[14][15]
on the northeast by a line running north 38º 30' west[a] from the southeast angle of lot number one, granted to Otho Reed, at the mouth of Gaspereau Creek in Port Elgin;
on the west and northwest by a line running up the Aulac River to the prolongation of Route 940 and Goose Creek Road, then by a line running northerly along the prolongation for about 4.3 kilometres, then running north 57º 30' east[b] the channel of Big Jolicure Lake, then northeasterly to the mouth of Goose Creek, then up Goose Creek and Robinson Brook to a point about 300 metres south of Brooklyn Road and 300 metres west of Luciphy Road, then northeasterly about 3.6 kilometres to Brooklyn Road, then north 45º east[b] to the starting point.
^The Territorial Division Act[2] divides the province into 152 parishes, the cities of Saint John and Fredericton, and one town of Grand Falls. The Interpretation Act[3] clarifies that parishes include any local government within their borders.
^"22 Vic. c. 9 An Act relating to the Boundary Line between the Provinces of New Brunswick and Nova Scotia.". Acts of the General Assembly of Her Majesty's Province of New Brunswick, Passed in March and April 1859. Fredericton: Government of New Brunswick. 1859. p. 52.
^"25 Vic. c. 32 An Act to explain an Act intituled An Act relating to the Boundary Line between the Provinces of New Brunswick and Nova Scotia.". Acts of the General Assembly of Her Majesty's Province of New Brunswick, Passed in March and April 1862. Fredericton: Government of New Brunswick. 1862. p. 101.
^ ab"43 Vic. c. 40 An Act to alter a portion of the Boundary Line of the Parish of Sackville, Westmorland County.". Acts of the General Assembly of Her Majesty's Province of New Brunswick. Passed in the Months of March & April 1880. Fredericton: Government of New Brunswick. 1880. pp. 80–81. Available as a free ebook from Google Books.
^ ab"57 Vic. c. 36 An Act to amend Chapter 2 of the Consolidated Statutes, of 'The division of the Province into Counties, Towns and Parishes,' so far as relates to the County of Westmorland.". Acts of the General Assembly of Her Majesty's Province of New Brunswick. Passed in the Month of April, 1894. Fredericton: Government of New Brunswick. 1894. pp. 162–163. Available as a free ebook from Google Books.
^ abc"No. 121". Provincial Archives of New Brunswick. Department of Natural Resources and Energy Development. Retrieved 25 June 2021. Remainder of parish on maps 122, 133, and 144 at same site.
^ abc"361"(PDF). Transportation and Infrastructure. Government of New Brunswick. Retrieved 25 June 2021. Remainder of parish on mapbooks 362, 382, 383, and 402 at same site.