Thanksgiving holiday traffic in Annapolis in 2015. (Jim Watson/AFP/Getty Images)

Several givens occur over Thanksgiving: You will go up a belt notch, and, unless you plan to eat a Swanson turkey dinner for one, you will join the millions of other feast-bound celebrants on the roads and rails and in the air. The November holiday is one of the busiest travel periods of the year, when Americans bombard the major modes of transportation over a five-day stretch. To prepare for the onslaught, we asked industry experts for their long weekend forecast plus some tips to reduce the stress beyond the dining room table.

Planes

According to estimates by the Airlines for America, an industry trade organization, 27.3 million passengers will fly globally during the holiday, a 2.5 percent bump from last year. In head-count terms, that means 55,000 more people will occupy plane seats each day. Passenger volumes will range from 1.51 million to 2.81 million, with the busiest travel days occurring — from highest to high-ish — on Nov. 27, Nov. 28 and Nov. 23. The lightest travel day: Thanksgiving itself.

More passengers means busier airports. A recent Orbitz report ranked the most-crowded airports over the holiday. Chicago O’Hare took the top spot, followed by Atlanta Hartsfield-Jackson and Los Angeles International. On the bright side, the slowest airports include Cincinnati/Northern Kentucky International, John Wayne International in Orange County, Calif., and Sacramento International.

Travelers planning to park at the airport should anticipate full garages and lots. Check availability in advance. Find real-time parking information for Washington Dulles and Reagan National at www.mwaa.com. At BWI Marshall, use Smart Park technology (electronic signage, green lights) to find a spot in the daily and hourly garages. You can also reserve a space with an online booking site or app such as SpotHero or AirportParkingReservations.com. For example, SpotHero listed a five-day holiday rate of $35 at the Crowne Plaza Dulles Airport Self-Park Garage. For Reagan National, you can also reserve through ePark.

The Post's Christopher Elliott shares some travel tips to get you through the busy Thanksgiving holiday season. (Erin Patrick O'Connor,Danielle Kunitz/The Washington Post)

To save time at the airport, print out your boarding pass at home or download the electronic boarding pass on your smartphone. Check the airport’s website for live security wait times; for PreCheck lines, go to apps.tsa.dhs.gov/mytsa/wait_times_home.aspx. To breeze through the queue, unwrap all presents packed in your carry-on. Also check TSA’s Can I bring my . . . tool to see if, say, your pumpkin pie is permitted onboard. (It is.)

For international flights landing at Dulles or BWI, download the free Mobile Passport App and speed through customs. Also, if you applied for Global Entry, the Trusted Traveler program, use it; if you don’t have it, get it.

Follow the airlines, airports and TSA on Twitter and Facebook for travel updates. If you have any flight issues, such as delays or lost baggage, reach out to the carrier through social media. The virtual help desk can often resolve a problem faster than the phone agent or beleaguered gate employee can.

Trains

Amtrak expects the same number of train riders as last year: 751,066 passengers during the Thanksgiving period. The busiest days will be the Tuesday and Wednesday before the holiday and the Sunday after the feast. With the exception of Thanksgiving Day, morning trains will typically have more open seats than afternoon and evening trains.

Brace yourself for crowded stations and snaking boarding lines. Arrive at least 30 minutes before departure time. Use the Amtrak app to check the status of departing and arriving trains. Passengers can bring two bags and two carry-ons weighing up to 150 pounds for free. If you have extra luggage or require special assistance, use the free Red Cap service, which is available at a dozen stations, including Washington’s Union Station, New York’s Penn Station and Philadelphia’s 30th Street Station.

Automobiles

Crank up the Enya on the car stereo because AAA expects 89 percent of travelers will slide behind the wheel this holiday. The organization anticipates 43.5 million roadsters countrywide, including more than a million from the Washington area, a six percent increase from last year.

A pardoned turkey smiles on the platform in Washington before catching the train to New York. (Chuck Gomez/Amtrak )

AAA says many merrymakers will start their drive 48 hours before the Thursday meal. The worst time to travel is between 5 and 6 p.m. on Tuesday. The Transportation Planning Board noticed the sharpest drop in average speed — about 20 miles per hour slower than “free flow”speed — during this period. Mid-Atlantic travelers should beware of chokepoints on the Capital Beltway between I-270 and I-95, U.S. Route 29 near Centreville, I-95 south and I-66. In Virginia, the heaviest traffic occurs after 11 a.m. on Wednesday and from 10 a.m. to 10 p.m. on Sunday.

When choosing between cars, you might want to take the hybrid instead of the SUV: Based on figures from Nov. 14, gas costs $2.17 per gallon, a 12-cent leap from last year. Diners can wax nostalgic about 2008, when the national gas average was $1.85.

Rely on apps for guidance and support. Some of the top road-related ones include AAA, Google Maps, Waze, GasBuddy, RoadTrippers, Beat the Traffic and Calm, a meditation app that claims to bring “peace of mind into your life.”

Correction: An earlier version of this story incorrectly stated Amtrak’s carry-on allowance. The story has been updated.

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