If your travel schedule will take you to the northeast next week — specifically to New York, Philadelphia and/or Washington D.C. — you might want to reschedule. If you can’t, you should study the itinerary for Pope Francis’ official visit to the U.S. and try to work your schedule around his.

Why? Because millions of the faithful are going to be thronging those three cities to get a glimpse of His Holiness, and massive security precautions will be in place — and the result will be overcrowded public transportation, massive street closures, monumental traffic backups and general chaos and disruption for visitors who need to get to a meeting.

The specifics: Pope Francis is due to arrive in the U.S. Tuesday afternoon at Andrews Air Force Base outside Washington. He’ll be in the nation’s capital on Wednesday and Thursday, September 23 and 24; on Thursday afternoon he flies into New York JFK, and he’ll remain in the city through Friday, September 25; he’ll fly out of JFK to Philadelphia Saturday morning, and he’ll be in Philadelphia Saturday and Sunday, September 26 and 27.

For starters, check out the official schedule for the Pope’s visit to see exactly where he will be in each city at which hours of the day.

Although Washington D.C. is no stranger to welcoming foreign dignitaries, the schedule of street closings and parking restrictions in the heart of the city is quite exhaustive for the papal visit. You can find all the details, hour by hour, at this website. In many cases, the closings will start hours before the Pope actually gets into the area.

In New York City on September 24 and 25, the traffic disruptions in midtown Manhattan will be truly epic, especially for the crosstown traffic that is usually backed up under normal circumstances. Again, the closures will begin well before the Pope arrives at specific locations. Read the details of all the street closures here.

The Port Authority of New York and New Jersey is warning travelers to New York City to use mass transit during the papal visit. The agency is planning to lay on extra trains and buses into the city to handle the crowds, and it cautions that all the street closings “may result in traffic congestion and pedestrian diversions in various parts of the city.”

Amtrak is advising travelers that if they plan on traveling by rail to Philadelphia on September 26 or 27, they will need a reservation for all trains, noting that the Pope is expected to attract more than a million people to the City of Brotherly Love. The rail service will also be scheduling a number of extra trains to handle the crowds.

Even if you hope to do nothing more than drive through Philadelphia on a major interstate highway that weekend, you could be forced to reroute yourself. Major highway closings will include I-76, I-676 and US Route 1. Philadelphia has designated certain “traffic boxes” in Center City starting Friday evening. What does a traffic box mean? It means cars will be allowed to leave the area but not to enter it, and there will be no bus or trolley service within it. You can see all the Philadelphia details here.  The city’s SEPTA regional rail and transit system will continue to operate that weekend, but trains will skip lots of stations when the Pope is in town.

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