Can you guess the worst day of the week for Seattle traffic?

KUOW listener Richard Smith thought he knew the answer but wanted to be sure: What’s the worst day of the week for traffic?

Reporter David Hyde with our SoundQs team looked into that for him and brought the answer to a conversation with KUOW’s Kim Malcolm.

And the answer … (drum roll) … is …

Thursday. (Smith guessed right)

The explanation:

Hyde: Trevor Reed with Kirkland-based traffic data company Inrix says Thursday afternoons are the worst period of travel in the Seattle area, especially 4-6 p.m. You're going to spend more time in heavy traffic on a Thursday than any other day of the week, especially Thursday afternoon.

And it's not just in Seattle. Reed said that traffic everywhere pretty much in the entire world is terrible on Thursdays. So the good news is we're not alone.

Why Thursday?

Hyde: That's the the deeper, more interesting, more complicated question. Inrix doesn't have a chip in your brain explaining why you're deciding to get on the road on Thursday.

But here are some possible reasons: One is that some people are working four 10-hour days so they're taking Fridays off. Or if you want a three-day weekend, you're going to take Monday or a Friday off.

But it seems like Friday afternoons are the worst to be in traffic.

Hyde: Friday afternoons are definitely still bad, because you've got people leaving for the weekends. But Reid suggested that the departure times on Fridays are a little bit more spread out. So that's the difference between Thursday and Friday. Congestion is worse on a Thursday. But of course this week with Thanksgiving, everything is up in the air.

So what’s the worst time to leave for Thanksgiving?

Hyde: Tuesday afternoon between 4 and 6 p.m.

Reid said in part it has to do with holiday traffic. People can't really shift their plans all that much. If you need to catch a flight, you need to catch a flight. You can't decide to leave later in the evening and so you're on the road.

The second worst time to leave for your Thanksgiving holiday is Wednesday at 10 a.m.

The best time: Leave at 2 a.m.

Any other advice for a normal Thursday?

Yes, leave work early. Reed said that if you can leave the office by 3 p.m., your trip will be up to 50 percent faster than it would if you leave at 4 p.m.

This conversation was edited for length and clarity.