Born and raised in Mississippi, the deep southern state with the most vicious reputation for racist violence - Martin Luther King described it in his 1963 "I have a dream" speech as "sweltering in injustice" - Hudson was years ahead of her time where civil rights activism was concerned. In 1937, while King was still a toddler, she went to Leake County Courthouse with her sister Dovie to try to register to vote "for the heck of it". It would be 25 years before she would succeed, and in the intervening years came tales of persecution and bureaucratic obstruction.

In 1961, she was passed a note as she went to the courthouse which read: "The Eyes of the White Knights of the Ku Klux Klan are upon you." A year later, she finally got the franchise, but only after she had written out and then explained a lengthy section of the state's constitution. "The more they did to us, the meaner we got," she said in an interview in 1994.

Born Winson Gates, she was the tenth of 13 children. Her mother, Emma Kirland, died when she was eight and she was raised by her father, John Wesley Gates, on a 105-acre farm until the land was seized by a white doctor as repayment for a family debt. When she was 19, she married Cleo Hudson and worked as a teacher at the local school, where the principal chided her for giving hungry children free bread.

"When she is speaking to you, her eyes hold you; at the same time, they seem to be scanning the landscape," wrote novelist Alice Walker after she met Hudson in the 1960s. "She is one of the 'sleepless ones' found in embattled Mississippi towns whose fight has been not only against unjust laws and verbal harassment but against guns and firebombs as well."

Hudson played an active role in the Mississippi Freedom Summer of 1964, when young activists from the north came down to help register black voters. Two of the three young men whose deaths were the basis for the 1988 film Mississippi Burning - James Chaney, Andrew Goodman and Michael Schwermer - boarded with her shortly before their deaths.

In an era of racial tyranny, her activism often cost her her job, forcing her to do manual work, and would leave her at times ostracised from a fearful black community. "We'd walk down the street in Carthage and you'd meet a black person going to borrow money or especially a teacher - they'd see you coming, they'd turn back. Some of them even ran from us," she once said. "It was a lonesome time, I tell you."

She died, after a long illness, in a hospital in Mississippi that she had fought to desegregate. She is survived by her daughter, brother, two grandsons and three great-grandchildren.

· Winson Hudson, campaigner, born November 17 1916; died April 24 2004