IAD or ORD?

What time of year?

Is there a meaningful difference of when you get home (PDX?)

ORD has a few more steps to get to your domestic flight. After clearing immigration, getting your luggage, passing through Customs (normally just a walk through), you have to get to another terminal for the flight to PDX unless you are on Delta or Frontier. You can recheck your luggage after Customs by just putting on the transfer belt. If you are going to another terminal, you then have to take the connector train to your terminal and go through security again. Even if you are on Delta or Frontier, I believe you still have to o through security again.

I have not used IAD, so I do not know if you have to go through security again.

PS, I believe only Alaska, American, and United have nonstops to PDX from ORD. All at different terminals than the International arrivals terminal (Terminal 5).

What airline?

And doesn't ORD often require a terminal change?

I fly United. I really like the mid-field immigration facilities below United's C/D Terminal at IAD. Immigration is usually a breeze, pick up bag walk 20 yards drop off bag and then through security, before popping back out into the C/D terminal.

All other things being equal, I would generally prefer to connect in Dulles rather than Chicago.

But all other things are not equal.

Among other factors I'd consider: seat comfort (on what plane, what airline, what cabin, seat dimensions, etc.). Schedule. Routing. Time of day. Time of year. One airline over another. Lounge considerations. Are there alternate flights available the same day in case your inbound flight is late and you can't make your planned connection? And cost differences.

In Chicago I've found connecting between international and domestic flights (separate terminals) can be an annoying hassle, requiring exiting your arrival terminal, finding, waiting for, then taking a bus (a crowded, slow, confusing bus, full of surly passengers and indifferent staff), then entering another terminal, with everything cobbled together in a hot mess. In Dulles, my experiences have been that the airport may not be an entirely delightful experience, but all I needed to do is walk a lot from one gate to another, without having to deal with bus rides between terminals. YMMV.

One other consideration: I hate connecting in the midwest or east coast and try to avoid it if I can. It breaks up the journey into two flights, neither of which is long enough to get any sleep, but both of which still seem long. I would much rather connect "out west" and maximize the length of the one, long, transatlantic leg, and have a shorter hop.

Given the Chicago versus Dulles conundrum, sounds like you're flying United to/from Europe. I'd greatly prefer a domestic connection in Denver or any west coast airport (even SFO or LAX, which may "look" out of the way), for a much more pleasurable experience. The flight times may not work easily for those United hubs, but I'd take them any day over Chicago or Dulles (or, god have mercy on your soul, Newark). IMHO it's worth a look to see if you can make your connection further west (a nonstop would be even better of course, but those cost more).

Hope something in there is useful.

PS: Dulles offers an occasional bonus - the possibility of having an encounter with a politician or someone else semi-famous. I once flew from Seattle to (I can't remember where) via Dulles, arriving on a monday after a long holiday weekend. After landing, I made a beeline for the nearest men's room. I noticed a well-dressed man coming off my flight doing the same. At first I didn't get a good look at him, but thought he looked familiar. Moments later I found myself in the men's room standing at a urinal next to him. We both finished our business and found ourselves next to each other again, washing up at a sink. This time I got a good look at him, we made eye contact, he smiled slightly and nodded at me (he was probably used to strangers recognizing him...). It was my US Senator (Bob Packwood - yeah, him). He was on his way to the senate for some vote on ending a government shutdown. I yelled something political at him as he briskly walked away.

We live in Oregon, too and hardly ever go thru PDX. We normally try to avoid Chicago and go thru Dulles.

Yes, United, and we will be flying next July. It sounds like Dulles has a much easier process, and arrival time in PDX is not significantly different. Good information, thanks. And absolutely, not Newark LOL. I think I will keep looking; I'd like to find something that connects in Seattle for sure.

Consider connections in Denver, too. United has been building up Denver for the past few years as a major western hub, with lots of international flights to Europe. From DEN it's just a quick hop to anywhere further west, and it's a pleasant airport to connect through. SFO, too but in recent years I've found myself connecting in Denver more often.

By July Alaska Air will/should have non-stop flights to Seattle from Rome, London and Paris.

The C/D terminal at IAD is all United. Your flight will land at a C or D gate and your domestic flight will then depart from a C or D gate. When you deplane, head down the hallway and stairs. There will be a very clear split in passenger traffic. Follow the signs for "Connecting Flights". These will direct you left and downstairs to the mid-field immigration facility located under Terminal C. Once downstairs, you will pass through passport control, pick up your bags, drop them at the recheck belt, and go through a dedicated TSA security checkpoint that puts you right back out into the C/D Terminal near gates C7 & C8

Avoid the "Main Terminal / Arrivals" signs. Do not follow the large crowds heading toward the Mobile Lounges. Taking those lounges will transport you directly to the main airport building arrivals hall, and you will not be able to easily return to the mid-field gate area

PDX here: I learned a few years ago I never want to make US landfall farther east than ORD, or IAH in a pinch. For me, I usually have to be up at the crack of yawn to may the first leg to a hub e.g., FRA/MUC/AMS/etc.. Then a layover. Then there's the transatlantic leg. Then another layover. Then the last leg, say EWR/IAD/ATL -> PDX.

IT'S ANOTHER SIX FREAKING HOURS TO PDX!!! Just. Shoot. Me. Now.

Last July I specifically booked FRA-SFO (11 1/2 hours) just so the last leg would be under two hours.

Ha, at least you are home when you get to PDX! I have a 3-hr drive afterward, so sad.

In Chicago I've found connecting between international and domestic flights (separate terminals) can be an annoying hassle, requiring exiting your arrival terminal, finding, waiting for, then taking a bus (a crowded, slow, confusing bus, full of surly passengers and indifferent staff), then entering another terminal, with everything cobbled together in a hot mess.

The bus is history. This was probably in 2019 or so when the people mover was being repaired and not operating. Normally there is no bus. Also adding (tho not relevant here) that all Delta domestic flights moved to the International terminal so SkyTeam arriving passengers (KLM, Air France, Virgin) can connect in the same building they arrive in. I'm not sure Delta has any international flights from/to O'Hare.

LAX, which may "look" out of the way

It looks out of the way BECAUSE IT IS!

ORD my home airport. I fly American. Here is what I hate about ORD once you land you may taxi anywhere from 10 minutes to more than an hour. A few weeks ago coming in from Vancouver we taxied for one hour forty minutes. That was fun after a four and half hour flight.

No storms. We were not early. Today 53 minute flight from Mpls taxied for 24 minutes & that was a short time. The time before same 53 minute flight taxied for an hour ten . It has become a game with my family. When I land I text so what is the over & under of when we will actually get to a gate?

It is not just American heard United same issues. Don’t know if it as bad for international landings. Vancouver was considered Domestic. We cleared emigration in Canada

If you have close connections I would worry. I can’t tell you how many times the flight attendants asks people to stay on the plane so tight connections can make it. Again international may be different. We did not fly direct on our last international flight to Europe last year.

One more point 2 1/2 hours may not be enough time. I honestly would want three hours to taxi, immigration & to get to terminal 1. Terminal 5 is international. Yes there is a tram outside security so you need to go through security at Terminal 1