Franklin won her fifth gold medal of the championships with an easy victory in the 200-meter backstroke Saturday, tying the record for most titles by a woman at the every-other-year world meet.
The 18-year-old Franklin has one event remaining the 400 medley relay and a chance to join Michael Phelps, Mark Spitz and Kristin Otto as the only swimmers to win as many as six golds at the worlds or the Olympics.
"That was awesome," said Franklin, who has already bettered her performance at the London Olympics, where she won four golds and a bronze. "The 200 back is my favorite race, but it's probably my most painful."
Ledecky, only 16, wrapped up a brilliant meet with her fourth gold medal and second world record, this time in the 800 freestyle. The youngster turned it on over the final laps to win in 8 minutes, 13.86 seconds. Ledecky took down the mark of 8:14.10 set by Britain's Rebecca Adlington at the 2008 Olympics.
Lotte Friis of Denmark set the early pace but settled for silver, and New Zealand's Lauren Boyle claimed the bronze.
Meanwhile, after an epic night of swimming, Ryan Lochte finally ran out of gas on his 29th birthday. He had the top time coming into the final of the 100 butterfly, but managed only a sixth-place finish. South Africa's Chad le Clos won the gold in 51.06.