The No.8-seeded Anisimova, a 24-year-old who was born in New Jersey and grew up in Florida, reached her third major semi-final and first at Flushing Meadows on Wednesday.
"To come back from Wimbledon like that is really special to me," said Anisimova.
"I feel like I worked so hard to try and turn around from that ... Playing here is so freaking special and I've been having the run of my life here.
"From the get-go, I was trying to fire myself up. She is one of the toughest players I've ever played. I knew I was going to have to dig deep."
On Thursday, Anisimova will try to reach a second consecutive major final. She'll face four-time grand slam champion Naomi Osaka after the No.23 seed beat Karolina Muchova 6-4 7-6 (7-3).
Osaka, who has never lost once she has reached the quarter-finals at a slam, said: "Last year she beat me when I had one of my best outfits. I'm just really grateful to be here. My dream is coming true."
Osaka practised with the 11th seed ahead of the tournament and had joked that the best thing about being seeded again was not having to face her in the first couple of rounds.
Both held their ground until the 10th game, when a break of the Muchova serve gave Osaka the opening set.
The Czech, who has been dogged by injuries throughout her career, headed off court for a medical timeout, returning with her left thigh strapped.
Muchova did not look at all comfortable but that did not stop her twice moving a break ahead in the second set, only to both times be pegged back immediately by Osaka.
Osaka refused to allow the contest to go to a decider, moving ahead early in the tiebreak and taking her second match point when her opponent drove a final forehand long.
The powerful strokes and poise Anisimova displayed earlier in Arthur Ashe Stadium against world No.2 Swiatek — the 2022 US Open champion — were such a striking contrast to what happened at the All England Club's Centre Court on July 12.
That title match lasted just 57 minutes, and Anisimova only managed to win 24 points that day, a total she eclipsed about midway through the first set in New York. Anisimova cried when delivering her runner-up speech during the trophy ceremony at Wimbledon.
"She moved better, she played better," Swiatek said, comparing this match to the one in London.
"Everything was different."
With PA.
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