In the United States, Mother's Day is held on the second Sunday in May.
Mother's Day was first celebrated in the churches and Sunday schools of Philadelphia in 1908. It was the idea of Anna Jarvis. When she was asked to arrange a memorial service for her mother, who lived in Virginia,
- there came to her a realization of the growing lack of tender consideration for absent mothers among worldly-minded, busy, grown-up children; of the thoughtless neglect of home ties and loving consideration, engendered by the whirl and pressure of modern life; of the lack of respect and deference to parents among children of the present generation; and of the need for a reminder of the loving, unselfish mother, living or dead.
It spread to other cities; in 1910 it was celebrated in Seattle. In 1912 it was celebrated by the entire state of Oklahoma. On May 8th, 1914, Woodrow WIlson signed House Joint Resolution 263, "A joint resolution designating the second Sunday in May as Mother's Day, and for other purposes." WIlson issued a proclamation "calling upon the Government officials to display the United States flag on all Government buildings, and the people of the United States to display the flag at their homes or other suitable places on the second Sunday in May, as a public expression of love and reverence for the mothers of our country." 
Notes and references
- Rice, Susan Tracey and Robert Haven Schauffler (1915), Mother's Day: Its History, Origin, Celebration, Spirit, and Significance as Related in Prose and Verse. New York: Moffat, Yard and Company.