"This is a dream come true, I can't believe I'm up there, I've wanted this for a long time," said Vanya Shivashankar, co-champion of the Scripps National Spelling Bee.
Her winning word was "scherenschnitte." She dedicated the win to her grandmother, who died in 2013.
"I'm literally ecstatic right now," she said.
Co-champion Gokul Venkatachalam, speller 140, said he had worked for six years to get to this point.
"I'm finally happy to have success," he said.
Vanya is the first sibling to win the championship. Her sister, Kavya, was the 2009 winner.
There have never before been back-to-back co-champions. Last year, Sriram Hathwar and Ansun Sujoe shared the prize.