Born in Philadelphia, Pennsylvania on February 12, 1776, Mary Young was the youngest of six children born to William Young and Rebecca Flower. Her mother, who became widowed when Mary was two years old, had a flag shop on Walnut Street in Philadelphia where she made ensigns, garrison flags and "Continental Colors" for the Continental Army. Her 1781 advertisement in the ""Pennsylvania Packet"" read, "All kinds of colours, for the Army and Navy, made and sold on the most reasonable Terms, By Rebecca Young." Young moved her family to Baltimore, Maryland when Mary was a child, and it was from her mother that Mary learned the craft of flag making.