I'm travelling from Amsterdam to New York with a stop in Reykjavik. I plan to only bring my 25L backpack. I've used it in Europe and I've found I can always buy what I can't carry. My bag is within the dimensions for carry-on luggage specified by the airline. I'm wondering: will not checking in any baggage draw suspicion (regarding me planning to leave the US again) from the TSA upon entering the US?
Normally I carry a small bag for the overhead compartment, but I was flying from Heathrow to NYC once and carrying only my baise en ville...
It caused me to get flagged up for further questioning by airline security (it was a US carrier). They were very worried that no baggage was checked and I had no carry on.
I was attending a party on short notice and fortunately had the invitation with me. I also explained that I was going to purchase some new clothes in Manhattan anyway (I explained also that I was born there and knew my way around, plus hotel reservations at the Marquis). So they let me go...
After this, my advice if you are travelling 'conspicuously light' is to have something on hand that demonstrates your itinerary and some plausible explanation for not carrying any change of clothes. I also switched to the Victorinox Altmont handbag after that incident, but this may be a spurious connection.
I live in the UK and until not too long ago, I used to fly between London (LHR) and Boston (BOS) quite often, up to a dozen times a year. Most of these trips to the USA were for short periods, the longest being about a week, but quite a few were literally for a weekend (i.e. flying to USA on Friday evening and flying back to UK on Sunday evening).
For most of these short trips I would only have a 25L backpack with me - with the minimum required stuff - and buying/obtaining anything else in Boston.
Most of the trips (but not all) were with Virgin Atlantic. Not once had I been stopped because I didn't check any bags. Once or twice I was selected for a secondary screening, where they would sift through my backpack - and then let me on the plane.
So I can say that not having any checked in luggage is not a problem in itself.
Note that I am a dual British/American citizen - and this may have had some impact.
Not at all.
I have friends who travelled all over South America and New Zealand with just carry-on 40L packs.
Many low-cost carriers these days also charge for luggage, so for example, when I fly from Sydney to Christchurch tomorrow (international) I am taking only carry-on - it saves me money, and it's fine for me to pack that light for a few days.
Based on my experience, the thing that's most likely to trigger extra security checks (at departure rather than arrival) is being a single male travelling on your own.
Every time I've travelled to US in that way, I've been pulled aside for extra security checks at the gate - always very brief and polite. I never experienced that doing similar trips when travelling as a couple or part of a larger group.
I just returned from a 12 day trip to Europe, flying in from Amsterdam to Detroit. I am a single male, 46 years old, U.S. citizen, and I only traveled with a 32.5L backpack as a carry on, and also carrying a small bag. Before I left customs in Detroit I was pulled aside and the entirety of my belongings were searched; they even flipped open the top of my dental floss and peaked in. They left me to pack most of it back up, and thanked me for my cooperation. I had nothing to hide, but still a little unnerving.