As an Englishman in New Haven, I couldn't help but notice last month's EN front page article about English preachers deserting England for America. I've met Ken Brownell once and know East London Tabernacle and was delighted with both experiences and interactions. I think Ken has a good point. Here's a different view.
The assertion, first popularised by Jim Packer, that American Christianity is a thousand miles wide but only two inches deep is intended as a perspective of the Bible belt. Actually, American Christianity as a whole is at least only 800 miles wide. That is, there are significant geographical and cultural pockets of America where gospel Christianity is a rarity. It's not that it's ephemeral or superficial; it doesn't exist. In particular, the North West of America and the North East of America are graveyards for gospel ministry.
New Haven is in the North East. It is also where Yale University is located. The other significant pocket of resistance to the gospel in America is not so much geographical as cultural. In the elite universities and in the hub centres of the cultural shapers of America, gospel Christianity has not made much of an impact. There are Christians around, they are just present in about the same proportions as you would find in England. And significantly less than you would find in Cambridge University (where I did student ministry for a good ten years) or, I believe, London as well.