There are a number of ways immigrants enter the United States illegally.  One of those includes flight.

During a discussion about President Donald Trump’s proposal to build a wall between the U.S. and Mexico, U.S. Senator Marco Rubio said, “In Florida, 70 percent of the people here illegally came on an airplane. They overstayed a visa."

PolitiFact Florida heard the claim and gave it a MOSTLY TRUE rating on its PolitiFact Truth-O-Meter.

Writer Josh Gillin said Senator Rubio, a Florida Republican, was talking in the context of how he didn't think Donald Trump's wall between the United States and Mexico was going to solve the illegal immigration problem.

“Now, Florida has a different kind of mix of immigrants.  It is not all people from Mexico or Central America.  They come from South America, they come from Europe, they come from all over,” Gillin said.

Gillin went on to say, while there's no government agency that really tracks visa overstays in this fashion, experts did calculate approximately 430,000 immigrants in Florida overstayed their visas.  That amounts to about 61 percent, not 70 percent

For that reason, Rubio's claim received a MOSTLY TRUE rating.

SOURCES:  Rubio says airplane immigrants overstay visas