Who has won the most US Open titles?

The tournament was first called the US National Singles Championship and was held in 1881 on grass at the Newport Casino in Newport, Rhode Island. Richard Sears was the inaugural champion after defeating William Glyn 6–0, 6–3, 6–2 in the final. 

In 1915, players signed a petition to relocate the tournament to New York as it was beneficial to host the national championship in that city.

In August of that year, the issue was decided through a vote and the tournament was held at the West Side Tennis Club in New York City for the first time, where Bill Johnston beat Maurice McLoughlin 1–6, 6–0, 7–5, 10–8 in the final. 

From 1921 to 1923, the Germantown Cricket Club in Philadelphia hosted the men's singles tournament but returned to the West Side Tennis Club in 1924 after its 14,000-seat stadium had been completed.

1924 proved a significant year, as the International Lawn Tennis Federation recognised the US National Singles Championship as a Major for the first time alongside the Australian Open, French Open, and Wimbledon. Bill Tilden defeated Bill Johnston in straight sets 6–1, 9–7, 6–2 in the final. 

Richard Sears, William Larned, and Bill Tilden hold the record for the most men's singles titles in the US National Championships with seven victories each.

In 1968, the US National Championships was renamed the US Open after professional tennis players were allowed to participate. Five years later, the US Open was the first major tennis tournament to provide equal prize money for male and female competitors. 

From 1975 to 1977, the US Open was played on clay before switching to the hard court surface after the tournament moved to play at the iconic Flushing Meadows in 1978. Jimmy Connors beat Bjorn Borg 6–4, 6–2, 6–2 in the final to become the only man to win the title on all three surfaces. 

Jimmy Connors secured five US Open titles in his career, a feat equalled by Pete Sampras and Roger Federer. However, Federer won five consecutive trophies from 2004 to 2008. 

Below is the list of the most successful tennis players who have won the US Open title.