Ruth Johnson Colvin, the founder of a literacy initiative that has taught millions of people worldwide, died on Sunday aged 107.

In the early 1960s, concern over low literacy rates in her community of Syracuse, New York, inspired Ms Colvin to launch a tutoring service in her basement that eventually grew into Literacy Volunteers of America.

In 2006, Ms Colvin received the Presidential Medal of Freedom, America's highest civilian honour, from George W Bush.

"When you look back over what happened in your life,” she recently told The New York Times, "you see the things that made you what you are. In my case, those things made me a very determined person."

"Ruth Colvin is a person of intelligence and vision and heart," Mr Bush said as he bestowed the her medal . "And she has earned the gratitude of many and the admiration of us all."

Ms Colvin was an avid reader but had no experience in teaching when she opened a classroom in her basement in the 1960s.

She recruited local volunteers to be tutors and taught thousands of people in her community basic language skills to help with education and job prospects.

"Don't equate ignorance with illiteracy," she later told the Associated Press. "People learn to get by... they contrive ways to work around it because they are too embarrassed to let anyone know."

In 1967, Literacy Volunteers was registered in New York State as a charity, then with 77 tutors and 100 students. In the years that followed, Ms Colvin's organisation earned various private and public grants, allowing the corps to grow across the country and, later, around the world.

In 2002, Literacy Volunteers of America merged with Laubach Literacy International to become ProLiteracy, now with some 10,000 tutors in 42 US states and 60 other countries, offering lessons in reading and writing.

And for six decades, Ms Colvin continued her work as a teacher, writing a dozen books about her experience. And she travelled frequently, checking in on literacy projects in foreign countries, often with her husband Bob Colvin. The two were married for 73 years, until Mr Colvin's death in 2014.

In an interview with The New York Times in 2020, at the age of 104, Ms Colvin said the secret to her longevity was "a balanced life".