Former world record holder Kathleen Baker was second in 58.56 and world bronze medalist Olivia Smoliga was third in 59.25.
The trio look poised for a monumental battle at the US Olympic trials in June, when only two swimmers can qualify to race the event at the Tokyo Games.
"It's great because it is such a stacked and talented field," said Smith, who also owns the 200m backstroke world record. "The crowd here really felt it and I felt really hyped up and excited. It was just such a great field and it just makes me really excited to race. It's nerve-wracking for sure but it's important to use those nerves in a good way and fuel them into your race."
In other events on the final day of the meeting, Caeleb Dressel won the 50m freestyle in world-leading 21.51 seconds, his second win of the week after his triumph in the 100m butterfly.