Traffic flows over the American Legion Bridge along I-495, the Capitol Beltway, on the day before the Thanksgiving holiday last year.  More than a million Washington area residents plan to travel this holiday. (Chip Somodevilla/Getty Images)

Thanksgiving is traditionally one of the busiest holiday travel weekends of the year and this year is no exception. Nearly 47 million Americans are expected to travel away from home over the long weekend according to forecasts.

And with low gas prices, AAA Travel projects this holiday could be the biggest travel-by-car event since 2007.

In the Washington region, more than a million residents will venture at least 50 miles from home, roughly about the same number of local travelers as last year.

“Curiously, the number of travelers departing from the Washington metro area will remain flat this Thanksgiving, despite an unemployment rate that continues to decline and the lowest Thanksgiving gas prices in seven years,” said John B. Townsend II, spokesman for AAA Mid-Atlantic.

Still, this holiday promises to bring one of the busiest travel weeks nationwide, and with so many people expected to get to their destinations by car, transportation officials and experts say planning is key as is arming yourself with plenty of time and patience.

In the Washington region, the exodus is expected to start early next week, with Tuesday afternoon likely the worst time to be on the road, according to an analysis of Thanksgiving travel by the region’s Transportation Planning Board.

The analysis of previous years found travel speeds on area roadways dropped well below average during the three days leading to Thanksgiving, but Tuesday was by far the worst. Travel speeds between 5 and 6 p.m. Tuesday were the lowest of the entire week and about twice as bad as a typical commute.

Wednesday was somewhat better. On the 14-mile stretch of I-66 West from the Capital Beltway to US 29 near Centreville, speeds slowed to less than 20 mph around 4 p.m. During a typical commute, those slowdowns are usually limited to the four miles between the Beltway and Chain Bridge Road, according to the report. In addition, holiday-related slowdowns began much earlier — around 11 a.m.

Meanwhile traveling through Maryland isn’t much better.  The Beltway between I-270 and I-95 was one of the worst to travel the Wednesday afternoon before Thanksgiving, with speeds in both directions slowing to less than 20 mph. During a typical Wednesday commute the average speeds generally don’t drop below 40 mph.

The staff of the D.C. region’s Transportation Planning Board created this helpful chart showing the slowest times for escaping traffic during Thanksgiving week. Tuesday afternoon was worse than Wednesday. (Transportation Planning Board image)

The TPB data suggests that the best times to travel during the three days leading to Thanksgiving are very early in the day, say around 6 a.m., and after 10 p.m. And don’t expect shortcuts and backroads to be any better. The Washington Post’s Dr. Gridlock, Robert Thomson, said at peak holiday travel times, many alternative routes also can get crowded.

“There aren’t any undiscovered shortcuts around the holidays. So most of my advisers in the traveling public say the best bet is simply to leave very early on those peak travel days,”  he advised on his weekly chat with commuters Monday. “Travel times during the Wednesday morning rush actually look better than travel times during the Monday or Tuesday morning rush. My guess is that this is because so many people have already left the D.C. area by the time we get to Wednesday morning.”

And car remains the preferred mode of travel for Thanksgiving. Nationwide, AAA projects that nearly 42 million people will get to their destination by car, an increase of about 0.7 percent over last year. The remaining travelers will fly or take other modes of transportation, including train and bus. See the details in this AAA chart.

In the Washington region, the majority –more than a million–  of those traveling say they plan to drive. More than 84,000 people are expected to fly and 25,200 will go by bus, train or boat, AAA said.

Many who are driving may be lured by the lowest gas prices in seven years. Nationally, the average price of gas is $2.16 per gallon, 64 cents lower than the average price for Thanksgiving Day a year ago. The average price in the Washington region Monday was $2.15 per gallon, 65 cents lower than the average in 2014, AAA said.

Remember stay tuned for the Capital Weather Gang‘s Holiday forecast this week, and Dr. Gridlock’s travel tips to be posted Wednesday morning. Also, this Sunday’s Commuter Page will have our complete Thanksgiving travel guide.