Longwood was the final home of the U.S. Pro where it was held from 1964 to 1999. It became part of the Grand Prix Tennis Tour shortly after the advent of open tennis in 1968. From 1970 to 1977, it was a prominent tournament of the Grand Prix Super Series. It then became a tennis event within the ATP Tour with reorganization of the top tier of pro tour tennis.
The tournament was later played on Har-Tru clay courts and was initially an important tune-up event for the US Open. But when this Grand Slam tournament moved to hardcourts in 1978, the U.S. Professionals did not follow suit, electing instead to hold its tournament during the US clay court season in early summer instead of during its hitherto pre-Open Era (late summer) time slot. Remaining a clay event into the 1990s, it was a non-ATP exhibition event from 1990 through 1995. During the last stint of the tournament, from 1997 to 1999, it was again an ATP event and was played on hardcourts.