Kate Hall was down to her final chance Sunday to win a second national high school title in the long jump, needing the best jump of her life to overtake her top rival.

She responded with a jump that surprised even herself.

Hall, of Casco, broke a 39-year-old national high school record with a jump of 22 feet, 5 inches at the New Balance Nationals in Greensboro, North Carolina.

Hall’s historic jump – her last of three attempts in the finals – puts her in a tie for ninth place in this year’s world rankings and tied for third among U.S. women with Brittney Reese, the 2012 Olympic gold medalist and a five-time world champion. It broke the oldest high school field event record – 22-3 set in 1976 by Kate McMillan of Raeford, North Carolina. McMillan won a silver medal at the 1976 Olympics.

Hall also broke the U.S. junior record (under age 20) of 22-3 3/4  set in 1982 by Carol Lewis, a bronze medalist at the 1983 World Championships and the sister of nine-time Olympic gold medalist Carl Lewis. And she surpassed the automatic qualifying standard of 21-11 for the 2016 Olympic trials, a mark Hall had been chasing all year.

Her best outdoor mark going into the meet was 20-11 last weekend at the New England high school championships. In March, she jumped 20-11 1/4 to win the high school indoor national championship.

“I skipped an entire foot. I was thinking tonight how years ago when I first went to nationals I saw people breaking national records. I never thought that it would be me,” said Hall, who competed for Lake Region High and will attend Iowa State this fall on a full athletic scholarship.

“I knew what the record was. And I thought that’s going to be really hard to break. It’s crazy.”

On Hall’s first jump in the finals, she took off well behind the board and was disappointed with her distance of 17-0. Her second attempt was on the board and was measured at 20-11, putting her in second place.

“If I jumped 21 feet and finished second, I would have been happy. But if I jumped 20-11 and got second, I would have been disappointed. That was going through my mind,” Hall said.

“I was crazy nervous inside. I don’t know how I stayed calm. I looked calm. But I was freaking out inside.”

She took two deep breaths to relax, and had the presence of mind to move her starting mark back a few inches.

“I wanted to try to relax. But everyone was clapping,” Hall said. “And when I push harder, I’ve learned sometimes I foul. So I moved the mark back a few inches (so I wouldn’t run too hard and miss the board).”

She hit the board and felt herself get more height than ever before.

When Hall saw the measurement, it took awhile for it to sink in, she said.

“I didn’t know it was 22 feet. I was hoping it was 21 feet. When someone told me, I was walking around crying, holding my head, covering my eyes,” Hall said.

Hall also finished third in the 100 meters Saturday with a time of 11.37 seconds – the fastest ever by a Maine woman. That time is 0.04 away from the qualifying standard for the U.S. national championships.

Hall, who was home-schooled, was coached throughout high school by a South Portland trainer, Chris Pribish, who owns The Medically Oriented Gym.

“She is a special athlete and she never lets us down,” Pribish said. “Words can’t explain how proud I am of her hard work and accomplishments.”

She ends her high school career with six New England titles, four New England records and two national-meet records.

And she has done all of it as a Type 1 diabetic with celiac disease, which means on a normal day she must check her blood-sugar levels five times.   But during competition she might check it that many times in a few hours.

With increased activity, blood-sugar levels drop because muscles use up sugar. When blood-sugar levels are too low, muscles perform poorly. If blood-sugar levels drop significantly, a person can lose consciousness. So Hall must constantly monitor her levels during the biggest competitions.

Yet throughout her high school career, Hall has continually raised the bar on her goals and performances. She said Sunday’s jump was far beyond her expectations.

“This is crazy to think I’m (ninth) in the world as a high school senior,” Hall said.