In 1912, Anna Jarvis said 'Mother's' should be what kind of possessive?

In 1912, Anna Jarvis said “Mother’s” should be a singular possessive.

Jarvis deliberately placed the apostrophe before the s in “Mother’s Day.” Her explanation was that each family should honor its own mother, rather than treating the holiday as a plural celebration belonging collectively to all mothers. She trademarked the phrase in 1912 while promoting the holiday through the Mother’s Day International Association.

The wording can be confusing because the modern holiday honors mothers generally. In ordinary English grammar, however, “mother’s” is the possessive form of the singular noun “mother,” while “mothers’” is the possessive form of the plural noun. “Mothers Day,” without an apostrophe, is simply a plural phrase and does not show possession.

Jarvis’s preferred spelling became the standard form in U.S. presidential proclamations and congressional legislation. She later became deeply opposed to the holiday’s commercialization, especially the sale of cards and flowers, but she continued insisting on the sentimental meaning represented by the singular possessive.