What drivers experienced during their Thanksgiving holiday is going to help them with the December getaways — up to a point.

Here’s how one traveler framed some key questions during my online chat Monday:

Q. I somehow managed to promise to be in NYC over Christmas while home for Thanksgiving. Yikes. I usually try to avoid traveling on the holidays that aren’t mandatory. So I have two vacation days that I can use. If I left on Saturday (Christmas Eve) would that be a horror show, or likely a bit after everyone else is on the road? I would prefer to drive when it is light, and I can’t imagine that Friday night (Dec. 23) would be anything other than just as horrible, if not worse. Probably would drive to a friend’s house on Long Island, take the train into Manhattan, then visit with the Long Island friends on Tuesday before leaving to drive back here on Wednesday.

DG: If you got away and got back safely last week, congratulations. You’ve endured the worst holiday getaway period of the year. There will be difficult travel times around Christmas and New Year’s, but for most drivers, they won’t match the depths of despair on Thanksgiving’s holiday highways.

The big difference is that people spread out their travel schedules at Christmastime. Schools are out, and many offices basically shut down at the end of the year. Some people stockpile vacation time for the end of the year.

Another difference between Thanksgiving and Christmas is an obvious one, but still important for travel planning. Thanksgiving is always on a Thursday, and for many people, it creates a four-day weekend. The travel effects of Christmas will vary depending on the day of the week on which it falls. The traveler bound for New York on Christmas Eve probably will benefit from that.

Despite those important differences between the holidays, travelers working out their December plans can still benefit from the Thanksgiving experience.

First, the experience of being delayed by highway congestion will be fresh in their minds. Even people who travel regularly at Thanksgiving can spend a year forgetting how bad the delays can be. That’s why my top tip in our Thanksgiving getaway guide — the most widely applicable tip — was “You’re probably not leaving enough time for the trip.”

From watching the regional traffic maps and cameras through the holiday period — plus some personal experience in traffic — I found the chart put out by the staff at the Transportation Planning Board to be a good predictor. Look at how travel speeds dip during a getaway period.

The chart shows the slowest times for escaping traffic during Thanksgiving week. (Transportation Planning Board image)

The Tuesday afternoon traffic last week was just ghastly. Wednesday afternoon was bad, too, but it did not look as deeply bad as Tuesday afternoon had. An early-morning getaway Wednesday would have worked well for many travelers. Thanksgiving Day was very good, especially in the morning, but it was not traffic-free.

Traffic data examined by the Transportation Planning Board and produced by the INRIX traffic information service suggest that, for Thanksgiving and other holidays, many travelers who can make an early getaway will do so. The Tuesday afternoon of Thanksgiving week is bad because it combines the early getaway traffic with the regular commuters who are still stuck in town.

With people’s travel habits in mind, look for some extra traffic on the afternoon and evening of Thursday, Dec. 22, though many will delay their departures till Friday. If you have that Friday off, consider a morning departure. It is likely that the Friday morning commuter traffic will be relatively light.

In the INRIX data for Thanksgiving weeks, the Black Friday shopping phenomenon shows up very strongly in traffic slowdowns around big shopping centers. So keep that behavioral pattern in mind if you’re planning travel Saturday, Dec. 24, which is likely to be a big day for the last-minute shoppers. They’ll be on some of our local highways along with the people who had no flexibility at all in their work schedules and had to wait till Saturday to launch their Christmas trips.

Here’s another difference between Thanksgiving and Christmas: The Christmas Day traffic is likely to be even better than the Thanksgiving Day traffic. People can wait till the holiday morning before driving to a Thanksgiving dinner, but many people want to be at their destination by Christmas morning.

The federal holiday for Christmas is Monday, Dec. 26. So many people will stage their return drives for that afternoon and evening. A return trip Tuesday — or Wednesday, as the Long Island-bound traveler plans — should work well.

The phenomenon that is most likely to mess with all of my travel predictions is the weather. Keep an eye on Capital Weather Gang forecasts.