How Hurricane Irma is impacting travel

— -- Hurricane Irma is about three days from making landfall in Florida, according to ABC News meteorologists, but the storm is already causing a statewide travel nightmare.

According to gas price watcher GasBuddy, the state's gas supply is starting to run out as residents rush to fill up their tanks. In Miami and West Palm Beach, nearly 35 percent of gas stations are out of gas, while Gainesville is reporting over 40 percent of its gas stations are out of gas.

Train travel will halt in much of Florida as well. Amtrak said in a statement all trains in and out of the state will be canceled starting Friday.

For those trying to evacuate by air, cancellations are beginning.

Key West International Airport originally closed Wednesday because the TSA initially planned to stop screening passengers. But the agency ultimately remained committed to screenings until Thursday evening, allowing Delta Air Lines to send three flights out of the airport, all bound for Atlanta. Non-commercial flights will continue until conditions become too dangerous. Commercial operations will be suspended after today.

By noon today, Miami International had canceled 120 flights and Fort Lauderdale International had canceled 48, according to Flightaware.com. Both Miami International's and Fort Lauderdale International's administrations have no plans to close their airports.

Over in central Florida, Orlando International will suspend commercial operations beginning Saturday evening.

American Airlines said in a statement to ABC News that the last flight out of its Miami hub will be Friday afternoon to Dallas.

A hurricane impacting a hub airport like Miami puts a strain on airlines out of that hub as well as the airport. United Airlines' hub in Houston, George Bush Intercontinental Airport, closed in late August because of Hurricane Harvey, causing a major impact to the company. United CFO Andrew Levy called it “the largest operational impact we’ve had in the company’s history.”

Overall, it is rare for an airport to close. There is a difference between an airport closing and ceasing commercial operations. An airport closes when there is or will be the possibility of serious damage. The last time Miami International closed was in 2005 during Hurricane Katrina. The storm damaged jet bridges and flooded parts of terminals. The FAA does not close an airport, rather the airport administration decides for itself to shut its doors.

However, when an airport ceases commercial operations, the airport will remain open but the airlines themselves will have canceled all their flights.

In response to how Miami International is preparing to this storm, an official told ABC News, “Prepare for the worst and hope for the best.”