"Success in the breaststroke and in swimming in general is about maintaining control," Kropp said. "I want to go as fast as possible in the first 100 but I don't want to die in the second half of the race."
The bronze effort qualified Kropp for Saturday evening's final, where she was estimated to finish fourth, according to the pre-race seedings.
"My goal for this race is to get as best a time as possible, make the national team and place better than I did last season," Kropp said.
Kropp also fared well in the 100 breaststroke, tying for 17th place (1:09.82) with Molly Hannis of Tennessee Aquatics.
Kropp's mark Thursday afternoon was slightly up from her prelims time of 1:09.72 swam earlier that day.
Swim Pasadena's Katy Campbell saved her best lap for last, anchoring in a time of 32.46 in the 800 freestyle prelims, while finishing 27th (8:48.99).
"I was really happy with my last 50 lap. I got it home quickly and improved on my time," Campbell said. "The best part with that time is that I get another chance to compete for an Olympic spot."
Campbell's mark was a personal best, her second of the week, as her mark of 4:14.16 in the 400 freestyle also broke a previous individual best of 4:19.
"It's definitely a different type of experience than swimming in high school or with your club," Campbell said in reference to the mostly adult lineup at the National Championships. "You see different people from colleges or professional adults."
The La Cañada High incoming senior competed in the 800 finals Saturday evening.
Current USC student Yumi So, who also represents Swim Pasadena and is a Crescenta Valley High product, concluded her five-event run with two competitions Friday.
So took 58th in the women's 200 butterfly in 2:16.83, a bit off her seeded mark of 2:12.57.
In the very next event Friday, So finished 151st in the 200 backstroke with a time of 2:22.58.