Rush hour traffic along Interstate 66 in Northern Virginia in this view from the Vienna Metro station. (Nikki Kahn/The Washington Post)

Labor Day marks the unofficial end of summer and millions of Americans are preparing to hit the road for the long weekend to squeeze in one last leisure trip.

It’s the holiday with fewest long-distance travelers, partly because the school year has already started in many districts. Still, transportation officials are asking travelers to prepare for traffic backups and delays.

Historically, when Labor Day weekend begins in August, as it does this year, Americans have shown a higher tendency to travel, said John Townsend, with AAA. Additionally, this summer was one of the busiest summer travel seasons on record. Townsend said as many as 35 million Americans and more than 800,000 Washington area residents may travel 50 miles or more this holiday.

Whether you’re planning to hit the road or stay in the Washington area, add in extra travel time. Even if you aren’t driving, getting around this weekend isn’t going to be pleasant. Track work will cause disruptions on some Metro lines, with some trains running only every 15 minutes. So, if you are planning to get to any events by Metro— including the National Book Festival on Saturday and the National Symphony Orchestra’s Labor Day Concert near the U.S. Capitol — plan on building in more time there too.

“It would be at record levels,” Townsend said of travelers. “If past trends hold true this Labor Day, holiday travelers departing the Washington metro area for the weekend will find slowing traffic beginning at 2 p.m. on Friday and the worst time to travel between 5-6 p.m,” he said. “The best bet for drivers is to wait until after 7 p.m. on Friday or before noon on Saturday to help ensure valuable vacationing time isn’t spent in standstill traffic.”

Those traveling by air should arrive at the airport early to make it through checkpoints. The lines to get through security have been longer this summer season, and are usually longer during the holidays. There have been several cases this summer of travelers caught with weapons at airport checkpoints, TSA officials remind travelers that weapons are not allowed in carry-on bags and guns in checked bags must be declared with your airline.

There is risk of popup storms Friday-Monday, according to The Washington Post’s Capital Weather Gang. Stick with them for updates.

Following is what you can expects on various modes of travel.

Metro

Labor Day service: Metrorail will open at 8 a.m. and close at 11 p.m. on Monday. Trains will run on a Sunday schedule and off-peak fares will be in effect all day. Parking is free at all Metro parking facilities on the holiday. Metrobus will run on a Sunday schedule, so prepare to wait longer at the bus stop. Reconstruction efforts in the rail system will continue throughout the three-day weekend.

Red Line: Trains will run every 8 minutes between Shady Grove and NoMa-Gallaudet from 9 a.m. to 9 p.m. and every 10 minutes from Fort Totten to Glenmont. After 9 p.m., trains will operate every 15 minutes. Remember that Rhode Island Avenue and Brookland stations remain closed until Monday, and shuttle buses will provide alternative transportation between those stations. This disruption isn’t new, but the good news is that it’s set to wrap up this weekend.

Orange Line: Trains will operate a normal weekend schedule. Metro announced that is has cancelled previously scheduled work that would have required trains to share a track between Clarendon and Foggy Bottom.

Silver Line: Metro has cancelled track work affecting the Orange, Silver and Blue lines. Regular weekend service is now scheduled.

Blue Line: Metro has cancelled track work on the Orange, Silver and Blue lines. Regular weekend service is now scheduled.

Yellow Line: Trains will run every 15 minutes between Huntington and Mt. Vernon Square.

Green Line: Trains will share a track between L’Enfant Plaza and Navy Yard to allow crews to install equipment to support cell service in the tunnels. Trains will operate every 15 minutes.

Maryland commuter services

MARC commuter trains will operate on regular Saturday and Sunday schedules this weekend, but there will be no MARC service on Labor Day.

Maryland Transportation Administration commuter buses also take Labor Day off, with the exception of the Route 201, which links the Gaithersburg Park & Ride to BWI Airport. The 201 will operate on a weekend/holiday schedule.

Beach bound and other traffic

Expect heavy traffic on the beach routes, including the very busy Chesapeake Bay Bridge in Maryland.

The Maryland Transportation Authority encourages drivers to plan ahead. The authority expects more than 2.1 million motorists to travel its facilities over the Labor Day weekend; traffic is expected to be 2 percent higher than last year. The authority expects more than 327,000 vehicles on the Bay Bridge (US 50/301) alone.

Drivers are encouraged to travel during the less busy hours: before 7 a.m. or after 9 p.m. Friday: before 8 a.m. and after 6 p.m. Saturday; and before 8 a.m. and after midnight Sunday and Monday.

In Virginia, motorists should expect high volumes of traffic on the 95 Express Lanes and 495 Express Lanes, as well as higher toll rates. Congestion is expected to be higher through Tuesday. Last year more than 250,000 trips were made on the 95 Express Lanes during the Labor Day weekend, according to the operator Transurban.

The best times to travel for outbound traffic is before 3 p.m. and after 7 p.m. Thursday and before 11 a.m. and after 9 p.m. Friday.

This post has been updated to reflect Metro's decision to cancel track work on Orange, Silver and Blue lines.