The Nova Scotia Federation of Municipalities (NSFM), formerly known as the Union of Nova Scotia Municipalities (UNSM), was established on August 15, 1906, during the Convention of the Union of Canadian Municipalities in Halifax, Nova Scotia, when Mayor Black of Wolfville motioned that a Provincial Union of Nova Scotia Municipalities be formed. After the benefits of a municipal union were discussed, the motion passed unanimously. Mayor R.T.MacIlreith of Halifax, and Halifax City Engineer F.W.W. Doane, were appointed President and Secretary, respectively.

At the first meeting, a constitution similar to those adopted by other provincial associations, was read clause by clause, and then approved. Fees were set in the following manner: Counties would pay $10; towns, $2 per thousand population (not less than $10 total); and cities, $2 per thousand population (not to exceed $50 total).

After its first year in operation, the Union generated $180 in fees from its 12 members. By August 1908, membership grew to 18 with $210 generated from fees. A membership of 50 was achieved at the time of the Seventh Annual Convention in 1912.

The Federation was established to protect the interests of municipal units in Nova Scotia. On August 28, 1907, at the Second Annual Convention, Mayor MacIlreith succinctly stated the raison d'etre of provincial unions of municipalities by noting that "organizations such as this (the UNSM) are charged with the particular duty of watching all legislation affecting the interests of municipalities." President A.E. McMahon noted at the UNSM Annual Convention on August 24, 1910, that the time will come when the government would rely more extensively on the Union's services and expertise. McMahon's premonition proved accurate, and, with time, an interactive decision-making process developed between the Province and the Union.

The NSFM increased its membership from 12 units to a high of 55 municipalities in the mid-1990s. Over time and through municipal amalgamation, the membership stands now at 49. While, in its present role, the NSFM does not assign committees to examine municipal expenses incurred in the suppression of infectious diseases as was the case in 1907, its mandate has not diverged greatly from Mayor MacIlreith's era. Although the visages of staff and elected officials have changed, the Federation's mandate is still, as much as ever, to protect the interests of Nova Scotia's municipalities.