On May 9, 1914, President Woodrow Wilson issued a proclamation establishing the second Sunday in May as a day for honoring mothers and calling on government officials to display the flag to show “love and reverence for the mothers of our country.” By this time most states had already made it an official holiday.
The San Francisco Call newspaper asked its readers on May 15, 1915 whether they had done anything for their mothers on May 9th (which, like this year, was a Sunday). “What did you do about it?” they asked.
After chiding its readers for neglecting Mother, the column ended with this call to action — not to give Mother flowers or brunch — but to give her the VOTE.
Women already had the vote in state elections in California (since 1911) and in several other (mostly Western) states. Not until 1920 would women throughout the United States enjoy the right to vote.
Note that last line — American Indians would not be classified as citizens with the right to vote until the passage of the Snyder Act in 1924.