The first female governor in the United States is Muriel "Ma" Sullivan, who served as the governor of Texas from 1925 to 1927. Her tenure was significant as it paved the way for women in leadership positions within American politics. Sullivan focused on social reforms and the advancement of women's rights during her time in office, making strides in education and healthcare. Her groundbreaking role as a female governor helped challenge gender norms and inspired future generations of women to pursue public office.