How and when was Mother’s Day originated in the United States?

Mother’s day, which is celebrated on the second Sunday in May, was first conceptualized in the U.S. in 1870. It was not however until 1905 that the Mother’s day celebration we know now was established. Anna Jarvis is recognized as the founder and “Mother of Mother’s Day.” Jarvis got the inspiration for Mother’s Day from her own mother as she wanted to honor all mothers, living and dead, and pay tribute to the contributions made by them. On May 10, 1905, the first Mother’s Day was celebrated in Jarvis’ hometown and by 1911 it was celebrated in almost every state. On May 8, 1914 President Woodrow Wilson signed a Joint Resolution designating the second Sunday in May as Mother's Day, thus making it an official holiday.

Source: http://www.mothersdaycentral.com/about-mothersday/history/