Margaret Tobin was born in Missouri, to her Irish immigrant parents, John and Johanna. She and her sister moved to Leadville, Colorado, when she was 18, where she got a job in a department store. She met, and married James Joseph Brown, (known as JJ), who was the son of Irish immigrants, as well. She had planned to marry a rich man, but, fell in love with JJ instead. They had two children, a boy and a girl. JJ was no slacker, and they came into great wealth because JJ knew engineering. Margaret became involved in women's rights, helping to establish the National American Woman's Suffrage Association (NAWSA), and she also worked in the local soup kitchens, helping to feed the poor families (usually miners) in the area.

The Browns eventually moved to Denver, where she became a charter member of the Denver Woman's Club, who claimed the mission of improving women's lives through education and philanthropy. In 1901, Margaret was one of the first women to enroll in the Carnegie Institute, in New York. She became fluent in French, German and Russian, and, ran for the US Senate.

After being married to JJ for 23 years, they amicably separated, and remained friends their entire lives. She received a cash settlement, a home in Denver, and a 700 dollar monthly allowance to continue her travels, and philanthropic activities.

And travel, she did. She boarded the RMS Titanic as a first class passenger, in France. When the ship hit its infamous ice bert, Margaret spent her time putting OTHER people in the lifeboats. She finally went off the ship in Lifeboat No. 6, which she quickly commandeered, and turned back towards the ship, to search for survivors. Thus, her nickname "The unsinkable Molly Brown". No survivors were found.

She decided, upon her return, to run for senate, again, but dropped out of the race. Her husband, whom she had not divorced, died, and left her some inheritance, of which her own children protested. She got her inheritance, and never spoke to her children, again. She continued, aided by her fame, to promote the issues close to her heart, women's, and workers rights, education and literacy for children, and she went to France to help rebuild areas damaged by WW I, and tend the wounded soldiers. There, she was awarded the French Legion of Honour. She died at age 65 of a Cerebral Hemorrhage.