She later attended the University of Michigan and received an M.D.. She became the fourth of six wives in a polygamous marriage to Angus M. Cannon, a prominent Latter-day Saint leader during the anti-polygamy crusade.

[3] The Hughes family were converts to the LDS Church and emigrated to the United States with their two daughters, Mary Elizabeth and Martha Maria.

The family accepted the invitation and traveled by train to Florence, Nebraska, and left with the Joseph Horne company on July 11, 1861.

Shortly before the family's arrival in the Salt Lake Valley, on September 3, 1861, Martha's sister, Annie Lloyd Hughes, died and was buried in an unmarked grave.

[1]: 9–12 At age fourteen, Hughes taught school for a year, but quit when she had trouble controlling her larger male students.

[1]: 10–11 In an October 1873 general conference address, Brigham Young encouraged women, specifically, to enter the medical field and become doctors.

The same year, at age sixteen, Martha Hughes enrolled in the University of Deseret as a pre-med major, working as a typesetter during the day while taking night classes.

[6] Hughes returned to Salt Lake City, Utah and opened a private practice in a new wing of the home built by her stepfather.

When Martha married Angus in the temple on October 6, 1884, becoming the fourth of his six plural wives, the marriage was kept secret as it was a religious ceremony rather than a legally binding contract.

Cannon joined the Mormon "underground" seeking to avoid providing federal marshals with proof of her plural marriage to Angus.

However, Elizabeth grew sick and Cannon, fearing for her daughter's life, moved to Wolverton near Stratford-upon-Avon to stay with other relatives.

Cannon wrote to Angus about Elizabeth's improving health also adding, "perhaps at this very moment you are basking in the smiles of your young Maria.

"[1]: 5  In 1887, Angus married Johanna Danielson, while Cannon was exiled in Europe, unable to return to Utah for fear of having to testify.

[6]: 38 [8]: 29–38 Correspondence between Cannon and her husband during this period provides a window into 19th-century polygamous life in Utah and also on "the underground" just prior to the practice's abolition.

In an effort to limit Mormon religious leadership in government, the act disenfranchised women of the Utah territory who had been voting in elections since 1870.

You give me a woman who thinks about something besides cook stoves and wash tubs and baby flannels, and I'll show you, nine times out of ten, a successful mother.She defended polygamy, believing wives in a polygamous marriage may in fact have more freedom than a monogamous marriage stating that if a husband had more than one wife, that wife had freedom in the weeks her husband was away visiting his other wives.

In February 1927, three decades after becoming the first women state senator of the United States, Cannon attended the 30th annual convention of the American Woman Suffrage Association in Washington D.C.[1]: 129 After 1888, Cannon resumed her Salt Lake medical practice and taught nursing courses through a school established at Deseret Hospital.

In a heavily publicized election, Cannon was one of five Democrats running as "at large" candidates for state senator from Salt Lake County.

[3]: 242–246 [11] Local and national newspapers gave play to the fact that a leading Mormon polygamist was defeated by his fourth wife.

The bill protected women and girls by requiring employers to give female employees something to rest on when they weren't serving customers.

In 1898 at the invitation of officials of the National American Woman's Suffrage Association, two years after becoming the country's first woman state senator, Cannon spoke at the Seneca Falls 50th year celebration in Washington D.C. Cannon also testified before the U.S. House Committee on the Judiciary of the positive effects of women's franchise in Utah.

[13] During the second half of her term in Utah's state senate, Cannon set up a commission that provided for regulations regarding contagious disease.

Disease grew rampant in the state of Utah, and the smallpox epidemic of 1898–1899 closed an entire town in Sanpete County.

To mitigate the effects of disease, Cannon eliminated communal cups attached to water fountains in Salt Lake valley.

At the end of her term, Deseret News wrote, "In political conventions, her wit, rapid thinking, and knowledge made her capable of holding her own and of representing her sex most favorably.

"[13] Cannon lost only one bill: an Act Providing for the Teaching in the Public Schools of the Effects of Alcoholic Drinks and Narcotics on the Human System[1]: 105–106 After leaving the legislature, Cannon still served as a member of the Utah Board of Health and as a member of the board of the Utah State School for the Deaf and Dumb.

[15] In 2020, Her Quiet Revolution, a historical fiction novel about Cannon's life and work by American author Marianne Monson, appeared in commemoration of the 100th anniversary of US women’s suffrage.