Airports for quick US entry.
 

A few years ago I flew LHR to Baltimore. I was off the aircraft and out of immigration and customs in about 25 minutes. I've just got back from Nashville and had a very similar experience on arrival - they have a small immigration facility but with only the BA flight and a couple of Mexican flights a week it clears quickly; only slight quibble is a longish walk from customs to the rest of the terminal to pick up car hire/taxi/hotel shuttle etc.

That said my record is prior to 911 at San Francisco in the "old" international building - 20 minutes flat plane to sidewalk.

What other US airports offer reliably (well, reasonably reliable) quick entry?

Toronto, Montreal, Vancouver are the ones I use. Perhaps Dublin might qualify also.

As 11277m indicated, pre-clearance at departure is the way to go if you want the fastest arrival in the US. Otherwise steer clear of the big hub airports and tourist areas - Cleveland used to be pretty good.

Recently arrived via Las Vegas, from getting off the aircraft to being landside was just under 30 minutes!

I've been off the plane and into my car at Newark in less than 30 mins. I usually take the early flight from Heathrow which gets in before 11.00am, when the arrivals hall is less busy than later in the day.

Don't fly to the US anymore (well not planning on it), but my trips to BOS via Shannon from LHR and the border check in Shannon and the walkthrough in BOS was a breeze. I think briefly in mid 1990's they did the border check at LHR too.

Tampa is pretty good, as the BA flight is the only international flight to arrive at that time of day. Downside, is that there are not that many desks, so you need to try and be one of the first ones off the aircraft.