The US Open first awarded equal prize money to men and women in 1973.
That year, the tournament became the first Grand Slam event to offer equal prize money in its men’s and women’s competitions. The singles champions, John Newcombe and Margaret Court, each received $25,000. The decision came during a period when women’s tennis was campaigning for better financial and professional equality.
The change occurred five years after the start of the Open Era in 1968, when professionals were admitted to Grand Slam tournaments alongside amateurs. The US Open’s move preceded similar changes at the other major championships, making it an important milestone in tennis history.
The answer is sometimes confused with 2007, when the French Open and Wimbledon finally matched the US Open and Australian Open in offering equal Grand Slam singles prize money. The question asks when the US Open itself introduced equality, making 1973 the canonical answer.