Makes sense. But why even give people access to their checked bags? I've never had a layover in another country, but I've been told that most other countries do not have flyers retrieve their checked bags, only to have to recheck them.

The US has vastly many more stations than any other country. Most of those have no CBP presence. Thus, CBP is done at the Port of Entry. You should not need to recheck your bag if connecting. Your bag should be checked to your final destination and simply dropped without a significant wait.

Maybe I should have explained my post better.

I recently did Paris -> Washington DC -> St Louis. I've done several international flights before, and have ALWAYS had to collect my checked bag at the arrival airport in the US (in this case, IAD), then walk with it for a few minutes, only to recheck it. In my case, I had to grab my checked bag at IAD, then recheck it to make its way to STL.

I've never had a layover in Europe, but have been told that you do not have to collect your checked bag. For example, if I flew JFK -> DUB -> CDG, I wouldn't have to grab my checked bag in DUB, only to recheck it again 10 minutes later.

Am I correct with this? Is there any reason that you have to recheck your bag in the US?

I think that what Often1 was saying is that the fraction of airports that handle international flights is much smaller in the US than in Europe. The theory is that it doesn't make economic sense to have CBP presence at all airports and therefore that you have to go through customs at the airport at which you first arrive from overseas.

That's different than in the Schengen area, where passport control is handled when you first arrive from outside the area, but where customs processing occurs at your final destination.

I understand that, but why is it required to grab your checked bag, only to have to recheck it again at a large airport like IAD or EWR?

Seems like they could just do the same thing they do with domestic layovers by automatically moving your checked bag to your next flight.

The majority of airports in the US don't have customs/immigration staff. If you fly LHR-SFO-BOI, for example, BOI almost certainly doesn't have CBP staff.

On rare occasions, this has really been handled badly for pax. For example, say your flight from LHR-SFO gets rerouted for some reason and is forced to land at BOI until the problems (engine, sick pax, threat, etc.) are resolved. Pax likely won't even be allowed to deplane, no matter how long it takes, because there is no CBP staff to clear them - even to enter the airport terminal to wait out the delay.

I understand that. However, I'm still not understanding why I have to grab my checked bag off a conveyor belt in SFO, only to check it again 20ft away.

Why can't SFO just automatically bring your bags to the plane going to BOI ?

Because between taking the bag off the belt in SFO and rechecking it, you pass through customs, a necessary step everywhere.

There is no customs staff in BOI.

Personally, I don't mind that nearly as much as I do having to go through TSA again to board my connecting flight.

So it's because your checked bag has to pass through customs with you?

Any reason they can't just automatically take your checked bag off the plane, scan it again, then move it to the next plane without the traveler having to touch it?

Seems like that could eliminate the TSA step as well.

Right, the bag needs to pass through customs with you so it can be subject to customs inspection. This is different than a TSA inspection.

The U.S. CBP sometimes uses slightly different procedures, for example at the YYZ preclearance area, where you don't generally need to pick up your bags when making a connection from a domestic Canadian flight. You have to wait for your name to appear on a screen, indicating that your bags have been received by the CBP. You then get in line for CBP processing. As the border officer processes your passport and declaration, he or she sometimes shows you a photo of your bags, asks you to verify that they are yours, and asks about their contents. If necessary, the bags can be retrieved for physical inspection.

It would shift the requirement to your final destination. Many (most) of those final destinations do not have customs staff to process your bags.

Some might only see a single international pax arriving in one day, perhaps less frequently. It's simply not financially feasible to provide CBP staffing at all those airports. CBP would insist on fully staffing for worst case scenarios, no matter how unlikely or costly.

I pointed out that this has occasionally been a real headache for pax. Your international flight gets diverted to Podunk, Mississippi because of weather. You land and sit for hours on the plane. Because there are no CBP facilities to process the pax, they're not allowed to deplane.

I'm not saying it's the best or only solution. I am just explaining why it is.

It's possibly the only reason the US doesn't have exit controls. That would require CBP staffing at every single commercial airport - or forcing everyone on a connecting flight to go through CBP at their connecting airport, an even bigger nightmare.

My biggest grip with having to go back through security in the US is the liquids limit.

I bought some alcohol in the Rome airport duty free shop one time not realizing that I would have to go back through security in the US. Luckily I was able to put it in my checked bag.

That has changed slightly.

If you buy the alcohol at a duty-free and they package it for you in a tamperproof bag, along with the receipt, you're supposed to be allowed to take it through the TSA checkpoint. You might want to do a search - it's been discussed elsewhere, but I haven't paid too much attention to how well it's actually working. As you might imagine, TSOs have every incentive to find something wrong - otherwise they have to buy their own liquor, and pax are usually bringing fairly decent stuff back.

As other have stated, there is a requirement in certain countries (Canada and USA are examples) for the traveler to cross customs area with all their belongings. These countries usually have low personal exemption limits for import duties, this becomes a taxation exercise.

The customs folks are also looking for items that are illegal in domestic country or have import prohibitions.

If you are looking for more information on the day in the life of a Customs Officer, check out this youtube link to Border Security a Canadian TV production.
If your bag happens to get lost, then you must fill out paperwork before crossing the customs area and then fill out more paperwork (declaration) when you pick up the bag.

The above procedures are new a represent a major investment by Canadian airports and Canadian government to facilitate cross border travel. The government program is called Beyond the Border. The airports have invested heavily in new technology to facilitate crossing the border without physically touching your bag.

Correct, the procedures for preboard screening are different in each country. Only Canada has facilitated cross border security screening. The Canadian TSA has implemented all US TSA procedures for preboard screening. This harmonization is also part of the Beyond Border program.

Airports and governments not willing to implement TSA or US government procedures will have arriving international pax subject to US government systems on arrival during a connection.

POISSON is confusing Customs (CBP) with TSA. The two have nothing to do with each other. It is also incorrect to suggest that one must recheck bags after Customs.

If you are connecting or are on separate tickets but your originating carrier is willing, your bags are checked through to their final destination. You need only drop them after Customs and need not wait at a desk to recheck.

The point here is that your bags are inspected somewhere. If you are connecting to STL, it would not matter so much, but the domestic carrier would have to separately tag and deliver arriving domestic and international bags and arriving passengers at STL would have to be sent to a CBP station. BOI doesn't have CBP, so it would not be a valid connection.

Bottom line is that it's apples and oranges to compare the UK, Schengen or almost any other nation for commercial air purposes.