(Claritza Jimenez,Danielle Kunitz,Julio Negron/The Washington Post)

If you’re visiting or planning to commute to downtown Washington on Inauguration Day, be prepared. As many as 1 million visitors are expected for the swearing-in of Donald Trump as the 45th president, the inaugural parade, the balls — and several planned demonstrations.

The good news is the federal and D.C. governments and the District’s public schools will be closed. But if you have business to conduct in the city, don’t plan on breezing in and out. Inauguration Day is a “National Special Security Event,” which means extremely tight security and significant road closures that will affect traffic and transit and will last through the weekend.

Friday’s events — the inauguration ceremony on the West Front of the Capitol and the parade along Pennsylvania Avenue — are likely to create the most disruptions. The road closures for the procession will affect downtown traffic and drivers coming in from Northern Virginia.

Restrictions went into effect well before the start of Friday’s 58th presidential inauguration. The kickoff celebration started Thursday, with a program at the Lincoln Memorial and a wreath-laying ceremony at Arlington National Cemetery. Saturday’s National Prayer Service at Washington National Cathedral will bring traffic disruptions to upper Northwest Washington.

In addition to traffic gridlock and road closures, be prepared for parking restrictions on streets across a large area of Capitol Hill, and for several blocks extending in every direction from the parade route along Pennsylvania Avenue.

“People need to plan ahead. They need to be prepared for crowds. They need to be prepared for winter weather,” said Leif A. Dormsjo, director of the D.C. Department of Transportation. “But if they have an interest in being a spectator on the Mall, because it’s a peaceful transition of power in our great democracy, they should certainly come on down.”

There are numerous road closures and parking restrictions in and around the Mall, some of which began as early as 3 a.m. Thursday (see our map). Vehicles will be ticketed and towed. In addition, restrictions and closures will affect streets around Capitol Hill, the Lincoln Memorial, Union Station, the Walter E. Washington Convention Center and Washington National Cathedral.

If you must drive — and we don’t recommend it — be prepared to drive around large perimeters and plot out alternative routes in advance. The road closures in a wide strip of downtown Washington, particularly for Friday’s events, could create traffic backups for drivers entering from the George Washington Memorial Parkway and Interstates 66 and 395. Incoming traffic from the 14th Street Bridge, Arlington Memorial Bridge and Rock Creek Parkway will be affected. Many of the road closures will last through the weekend. You should expect delays in many parts of downtown and avoid driving near those ­areas.

Metro: Transit is your best bet for getting around through the weekend. On Inauguration Day, Metro will open at 4 a.m. and close at midnight. Trains will run rush-hour service from the opening until 9 p.m., which means peak fares will apply for 17 hours.

Five Metro stations will be closed because of security concerns: Archives, Federal Triangle, Smithsonian, Mount Vernon Square and Pentagon. Additional station closures are possible, Metro said.

Metro is offering a Commemorative Inaugural SmarTrip card at a discounted price of $10; the card comes preloaded with a one-day pass that is good for unlimited Metrorail and Metrobus use on Inauguration Day. Riders are encouraged to purchase SmarTrip cards in advance to avoid the crush at fare machines. Each rider age 5 or older needs their own card to enter the system. Metro officials also recommend that you plan your trip so that you don’t have to transfer between lines: There is a station near the Mall on each line.

And be prepared. Make sure your SmarTrip card is loaded with enough fare to travel during the day. Use Metro’s Trip Planner (www.wmata.com/schedules/trip-planner) to plan and price your route.

Parking: Metro has about 60,000 parking spaces in 29 lots and 22 garages throughout the region available for use on Inauguration Day. Regular weekday parking rates will be charged. You pay by credit card upon exiting the facilities. Parking facilities will fill up quickly, so make sure you have a plan B.

Charter buses will be able to park only at RFK Stadium and must reserve a spot. As many as 1,500 private buses carrying about 100,000 people are expected for the inaugural events. From RFK Stadium, visitors can ride Metro, walk or take shuttle buses to the Mall.

Metrobus: The bus system will operate on a Saturday schedule, with additional trips on some routes. Expect detours around inauguration events and road closures.

About 50 bus routes will be affected by road closures and will be detoured around inauguration events. The bus lines that cross the Mall will be turned around the parade perimeters.

The Pentagon Transit Center will be closed. All routes that serve the transit center will begin and end at Pentagon City.

Temporary bus stops will be marked around the security perimeter of the event where bus routes end. If you plan on riding the bus, get a SmarTrip card. Otherwise, you must have exact change; bus operators do not carry money. The regular Metrobus fare is $1.75 using a SmarTrip card or cash, or 85 cents using a Senior SmarTrip card or cash (with proper ID) for seniors and people with disabilities.

Pedestrians and viewing areas: Mall access points (which include bag checks) will be on Constitution Avenue at Seventh, 12th and 17th streets NW; and Independence Avenue at Seventh, 12th, 15th and 17th streets SW.

For those walking to the Mall, Union Station is the recommended east/west divide on the north side of the parade route.

Keep in mind that the Metro stations closest to the Capitol may not be the best options to use if you are going to the parade. Metro recommends using others. For example, Farragut North on the Red Line and Farragut West on the Blue, Orange and Silver lines are about a mile walk from the Mall. L’Enfant Plaza, served by the Blue, Orange, Green, Yellow and Silver lines, is about two blocks from the Mall. Metro Center is about a 1.7-mile walk going around the Pennsylvania Avenue barriers.

The recommended Metro exits for those with tickets to the inaugural ceremonies are Capitol South, Eastern Market, Union Station, NoMa-Gallaudet U (New York Ave.), Judiciary Square, Gallery Place-Chinatown, Federal Center SW and L’Enfant Plaza.

Viewing the inaugural ceremonies from the Mall does not require tickets. But bags will be checked. The non-ticketed area of the Mall begins at Fourth Street NW and extends past the Washington Monument to 17th Street NW. The Washington Monument viewing area will be restricted to the grounds between 17th and 15th streets NW.

Prohibited items: Aerosols; ammunition; animals other than service or guide dogs; large backpacks; balloons; bicycles; coolers; drones; explosives; firearms; glass, thermal or metal containers; laser pointers; mace or pepper spray; packages; selfie sticks; structures; supports for signs and placards; toy guns; weapons of any kind; and any other hazardous items.

MetroAccess: The paratransit service will operate the same hours as Metro, but riders should expect detours, delays and service adjustments. MetroAccess customers should allow extra time because of increased traffic. Officials urge customers to consider the possible lack of access to and from the events as they plan their visit.

D.C. Circulator: The city’s bus system will suspend service on four routes: Union Station-Navy Yard, Mall, Rosslyn-Dupont and Georgetown-Union Station.

D.C. Streetcar: The service will extend its hours, starting earlier than usual. It will start running at 4 a.m. Friday. It will close at the usual 2 a.m. Saturday. The streetcar is free to ride and runs at about 10- to 15-minute intervals.

Maryland Transit: MARC commuter rail service will run on a special schedule on Inauguration Day, with trains operating into Washington in the morning only and returning from the District in the afternoon to early evening only. There will be no Camden Line service.

Commemorative tickets will be available for sale at the Odenton and Frederick stations up to Inauguration Day. The round-trip day pass ticket costs $20 on all Penn Line and Brunswick Line trains departing Maryland stations and $30 from Brunswick Line stations in West Virginia. MARC weekly and monthly multi-ride tickets will be honored, and passengers may also purchase regular one-way tickets. Schedules for Inauguration Day trains can be viewed on the MTA website.

On Inauguration Day, trains will not stop at Bowie, Seabrook and New Carrollton on the Penn Line or at Rockville, Garrett Park, Kensington and Silver Spring on the Brunswick Line. Passengers needing those stops should use Metrorail.

Virginia Railway Express: The commuter trains from Manassas and Spotsylvania will run on an “S Schedule,” or reduced service. Only trains with an S above the train number on the schedule will operate. For details, see VRE’s schedules online.

Taxi and rideshare services: You should be able to take a taxi, Uber or Lyft to the entrance of the secure inaugural area, but know that traffic could slow your trip. If you’re planning to use one of those services, be prepared to walk from the restricted area to catch one. Taxi stands will be set up in Hill East, L’Enfant Plaza, Mount Vernon Square and the Kennedy Center.

A “geofence” will be in effect around the Mall on Friday, so visitors won’t be able to contact services such as Uber and Lyft from inside the perimeter. Several zones have been created nearby to allow Uber and Lyft drivers to wait for customers. Keep in mind that there’s a possibility surge pricing will be in effect.

Capital Bikeshare: To use the Bikeshare system you must first become a member, and there are various membership options — from 24 hours to annual. The system will offer two “corrals” on Inauguration Day to provide extra parking during the festivities. The corrals will be at 17th and K streets NW and at Fourth and E streets SW. Bikeshare stations in the Mall area will be closed Thursday and Friday. For more information, visit ­capitalbikeshare.com

If you are biking on your personal bike to downtown, bike parking will be free at 16th and I streets NW.

Airports: Air travelers should anticipate crowding and congestion at the region’s airports from Thursday through Sunday. The roads around Reagan National Airport are scheduled to be open Inauguration Day, and that includes the George Washington Parkway. Airport officials say the influx of travelers for inauguration events could mean longer-than-usual wait times at ticket counters and security checkpoints, as well as extra traffic on the airport roads. If you park in the airport garages, consider reserving a spot.

So if you are planning to participate in the weekend’s events, be ready to witness some of the strictest security measures and protocols in Washington.

Though this year’s crowds are not expected to be as high as eight years ago, when President Obama’s first inauguration drew 1.8 million people to the Mall, it will still be a mass of humanity.

The bottom line, officials say: Go with a plan and don’t panic if you get lost or have questions along the way. City employees will be stationed across the downtown area to help guide you to the Mall or provide medical assistance.

“Transit and pedestrian movement is going to be the name of the game on Friday,” Dormsjo said.

Martine Powers contributed to this report.