Mother's Day is the second Sunday of May each year.
On May 9, 1914, President Woodrow Wilson proclaimed that the observance of Mother's Day on the second Sunday in May serves as a "public expression of our love and reverence for the mothers of our country."
Mother's Day was initiated on May 10, 1908 in Grafton, West Virginia. On that day, Ann Jarvis organized a celebration at the Andrews Methodist Episcopal Church, now called the International Mother's Day Shrine (a National Historical Landmark), with 407 children and their mothers in attendance. The custom caught on and led to the Federal observance in 1914.
Jarvis trademarked the phrases "second Sunday in May" and "Mother's Day" - purposefully putting the apostrophe before the "s" as the holiday is for each family to honor their mother.
Mother's Day is not considered a Federal Holiday. It is considered a day of Federal "observance" - a reminder to pause and show appreciation for all of the mothers in our lives.
West Virginia Governor William Glasscock's Proclamation of Mother's Day Dated April 26, 1910