Although born in the UK, Elizabeth Blackwell moved to the USA at 11. After her father's death when she was just 17, Blackwell, with her mother and sister opened a school.
Blackwell later decided to study medicine and was accepted by Geneva Medical School, New York in 1847. Having previously studied privately, she graduated in 1849 - the first woman to receive a medical degree in the United States.
Blckwell practiced medicine in the US, England and Europe and later became involved in Social Reform work. In the late 1860s, Blackwell opened a medical school for women - the Women’s Medical College of the New York Infirmary.
http://www.biography.com/people/elizabeth-blackwell-9214198
Sarah Hackett Stevenson, 2nd Feb 1841 - 14th August 1909
Sarah Stevenson was an American Physician and the first woman to be a member of the American Medical Association. She gained her first degree in 1863 and graduated as an MD in Chicago in 1874.
In 1880, Sarah Stevenson and Lucy Flowers founded the Illinois Training School for Nurses.
Winifred Goldring, 1st Feb 1888 – 30th Jan 1971
Winifred Goldring was an American Paleontologist and was the first woman to hold the position of State Paleontologist.
Goldring was an authority on stromatolites and Devonian Crinoids.
In 1949 she was elected president of the Paleontological Society, a position (even now) only held by two women in a male dominated field