There is a long history of women appearances in mathematics in the United States. All women mentioned here are American unless otherwise noted.
Timeline
19th Century
1829: The first public test of an American girl in geometry was held.[1]
1886: Winifred Edgerton Merrill became the first American woman to earn a PhD in mathematics, which she earned from Columbia University.[2]
20th Century
1956: Gladys West began collecting data from satellites at the Naval Surface Warfare Center Dahlgren Division. Her calculations directly impacted the development of accurate GPS systems.[3]