An expanded version of America's annual Thanksgiving travel saga has begun with gas prices low and terrorism fears high.

An estimated 46.9 million Americans are expected to take a car, plane, bus or train at least 50 miles from home over the long holiday weekend, according to the motoring organization AAA. That would be an increase of more than 300,000 people over last year, and the most travelers since 2007.

Among the reasons given for the increase: an improving economy and the cheapest gasoline for this time of year since 2008.

With prices falling for 17 consecutive days, drivers are getting a total of 15 cent savings per gallon in many parts of the U.S.

But the drop isn’t expected to stop.

The national average retail price of gas is expected to fall below $2 per gallon by the Christmas holiday. Some stations around Central Florida are already selling gas for less than $2 per gallon.

The roads will be busy, too

The night before Thanksgiving is one of the most dangerous nights to be on the roadways. Often called Blackout Wednesday or Drinksgiving, many people spend Wednesday night at the bars while they are home for the holiday weekend.

The National Safety Council estimates 433 people will be killed and another 52,300 will be seriously injured in car crashes across the country over the next five days.

Law enforcement agencies across Central Florida said they will be stepping up patrols to nab drunk drivers.

AAA and Anheuser-Busch are urging everyone to have a safe Thanksgiving by choosing a designated driver, staying where you are celebrating, using a cab or finding another form of sober transportation, such as Tow to Go.

Whether you are an AAA member or not, you can call for a Tow to Go ride at (855) 2-TOW-2-GO or (855) 286-9246 any time Wednesday through Saturday night.

AAA will then safely transport you and your vehicle home or somewhere safe within 10 miles.

According to AAA, 20 percent of drivers in the southeastern United States have never used a designated driver when they’ve been away from home and drinking.

Information from The Associated Press was used in this report.

— News 13 Reporter Jerry Hume contributed to this report from Orlando.