U.S. Sen. Ted Cruz's presidential campaign announcement Monday led some to question how the Texas Republican can run to be the United States' commander in chief when he actually wasn't born in the country. Cruz was born in Calgary, which lies in the Canadian province of Alberta, to an American mother and Cuban father in 1970. The U.S. Constitution dictates that in order to run for president, a candidate has to be a natural-born citizen.

So is Cruz, who opponents nicknamed "Canadian Ted," still eligible? Short answer: yes.

Long answer: Because Cruz was born on Canadian soil to an American mom, he got dual citizenship. And "because I was a U.S. citizen at birth, because I left Calgary when I was 4 and have lived my entire life since then in the U.S., and because I have never taken affirmative steps to claim Canadian citizenship, I assumed that was the end of the matter," Cruz told the Dallas Morning News in 2013. 

But he technically still was a dual citizen. To remedy this -- and likely to prepare for his presidential run -- the senator officially renounced his Canadian citizenship. CNN reported the paperwork cleared last spring, and Cruz received a letter certifying that he ceased to be a citizen on May 14. "It's official, y'all," his spokeswoman, Catherine Frazier, tweeted. 

The issue of presidential candidates' citizenship has come up before. President Barack Obama was famously grilled over being born in Hawaii to a Kenyan father, which led the White House to eventually publish his long-form birth certificate. Republican presidential candidate John McCain was born in the Panama Canal Zone, Yahoo reported.

"As Congress has recognized since the founding, a person born abroad to a U.S. citizen parent is generally a U.S. citizen from birth with no need for naturalization. And the phrase 'natural born Citizen' in the Constitution encompasses all such citizens from birth," legal authorities Neal Katyal and Paul Clement wrote in a Harvard Law Review article. "Thus, an individual born to a U.S. citizen parent -- whether in California or Canada or the Canal Zone -- is a U.S. citizen from birth and is fully eligible to serve as president if the people so choose."