Clarke, Mary Frances (1803/6–87), founder of the Sisters of Charity of the Blessed Virgin Mary, was born either on 2 March 1803 or 1806 in Dublin, the eldest of four children of Cornelius Clarke, leather dealer, and Catherine Clarke (née Quartermas), daughter of a quaker from England. After being educated at a penny school in Dublin and by private tutors, she worked as a bookkeeper in her father's leather and harness shop. When her father became an invalid after a work accident, she assumed the management of his business. During the cholera epidemic of 1831 she met four other women while helping the sick, and the following year they started a school, Miss Clarke's Seminary, at the corner of North Ann Street and Cuckoo Lane in Dublin for girls who were unable to afford convent school fees. In 1833 these women were persuaded by an American priest to transfer their charitable work to the USA. They arrived in Philadelphia on 10 September 1833, where they undertook the establishment of a school for the children of Irish immigrant textile workers in the city.
Under the mentorship of Rev. Terence J. Donaghoe, a native of Tyrone, the five women established a pious organisation, the Sisters of the Blessed Virgin Mary (BVM), and on 1 November 1833 made acts of consecration. Clarke was elected the first mother and Donaghoe was superior. In 1843 five of the members accepted an invitation by Bishop Mathias Loras of the Dubuque diocese in the Iowa Territory to establish a school for the education of Native American and pioneer children. Their first school, St Mary's Academy, established 23 June 1843, was in a log cabin. On 8 September 1843 the remaining 14 sisters and Donaghoe also arrived in Dubuque, leaving Philadelphia because of ecclesiastical politics and nativist antipathy towards Irish immigrants. Upon their arrival, Loras conferred canonical status on the community, which now became an official women's religious congregation. They added ‘Charity’ to their name and began to wear a religious habit. They built their first motherhouse ten miles from Dubuque on the Iowa prairie. Donaghue, who had been Loras’s vicar general, died 5 January 1869, and Clarke then assumed both titles of mother and superior.
In 1869, when Iowa achieved statehood, she incorporated the congregation as a not-for-profit corporation, and obtained papal approbation in 1877. The sisters continued their work in education, and established schools along the Mississippi River and western railway lines. Clarke kept in touch with her sisters through extensive letters and was recognised as a compassionate and collaborative leader. The final foundation before Clarke's death was St. Brigid's parish school in San Francisco (1887). Clarke died 4 December 1887 in Dubuque, Iowa. During her 54 years as head of the congregation, she oversaw the foundation of 40 parochial schools and nine boarding academies. During this time 444 women joined the congregation, many of whom were young pioneers. Clarke was inducted into the Iowa Women's Hall of Fame on 27 August 1984, in recognition of her role in the education and religious formation of the American frontier.