His mother was born in Connecticut. She was working in Canada when Cruz was born. Her AMERICAN-BORN CITIZENSHIP automatically made him an AMERICAN CITIZEN. While he was born in a Canadian hospital (because his mother lived there), his Canadian citizenship is just an afterthought. And, Cruz has ready dismissed his Canadian citizenship .. which leaves him as ONLY - AN AMERICAN CITIZEN.
The story goes that his mother became a Canadian citizen...And Canada doesn't recognize dual citizenship...