Rosa Parks was a 42-year-old seamstress living in Montgomery Alabama.
On 1 December 1955, she waited for the bus after work, like she always did.
She got on the front and paid her fare, like she always did, then she had to get off again and got on at the back of the bus, where black people had to get on.
Blacks weren’t allowed to get on at the front, like whites, so she got on at the back and sat in the black section.
But then a white man got on, and there were no more seats in the white section.
So the driver said a black person had to get up and give the white man his seat, and all the black people in that row had to get up, as they couldn’t sit in the same row as a white person.
So four black people had to get up so a white man could sit down.
That’s when Parks decided she’d had enough.
That wasn’t fair, that wasn’t right, the other three moved but Parks didn’t.
The bus driver, James F Blake, said to her: "Why don’t you stand up?"
She said: "I don’t think I should have to."
He said: "If you don’t, I’m going to call the police."
She said: "You may do that."
The policeman arrived, she said to him: "Why do you push us around?"
He said: "I don’t know, but the law’s the law and you’re under arrest."
Parks was taken to jail, but what happened next makes it really interesting.
Instead of rioting or protesting, the black community in Montgomery did something that was much more effective.
They circulated 35,000 leaflets around Montgomery declaring a bus boycott:
"We are asking every Negro to stay off the buses Monday in protest of the arrest and trial.
"If you work take a cab or walk. But please children and grown-ups, don’t ride the bus at all on Monday. Please stay off the buses Monday."
Seventy-five per cent of bus passengers were black, so, just like that, they lost three-quarters of their income.
That protest went on for 381 days, during that time most of the buses and staff sat idle and the bus company was facing financial ruin.
Six months later, in June 1956, the district court declared segregation illegal.
Six months after that, the Supreme Court declared segregation unconstitutional.
With the bus company about to go bankrupt, they had no choice but to de-segregate.
Parks sparked the movement that culminated in the Civil Rights Act of 1964, and the Voting Rights Act of 1965.
For the first time, black Americans saw that they were a powerful financial force.
Simply by removing their trade they could force change.
The bus company didn’t give in because it was the right thing to do, it gave in because it cost it money.
In 2019, Nielsen reported that African-Americans represent 14% of the population but are responsible for $1.2tn spending power.
They dominate some markets: 50% of dry grain and vegetables, 42% of baby food, 41% of soap and bath products, 37% of juices and drinks.
Because of the bus boycott African Americans were able to demand that if anyone wants their money, they have to treat them like humans.
Procter & Gamble is now the largest spender in African-American media, at more than half a billion dollars.
Parks became known as "The mother of the civil rights movement".
When she died, she became the first woman to lie in state in the rotunda of the Capitol Building in Washington DC.
As she said: "They say I stayed seated because I was tired. But the only tired I was, was tired of giving in."
Dave Trott is the author of Creative Blindness and How to Cure It, Creative Mischief, Predatory Thinking and One Plus One Equals Three