I'm a Canadian citizen who was born and lived in UK all his life who lives and works (legally) in the US for 4 years on a non-resident TN visa,
I'm not allowed to be considered even a temporary resident in the US despite the fact I've lived here for 4 years, oh but I am considered resident for tax purposes (ie I pay tax here and do a US tax return - but no other residency benefits).
When I arrive back in the country I have to say on my landing card that I'm temporally visiting the US and that I'm a resident of the United Kingdom. However, I don't pass the "residency test" of the UK as I've not lived there for 4 years. Technically I'm not resident of any country, which is kinda unsettling. And I'm 'temporally visiting the US' in that I drive out of the airport in the car that I own here and drive home to my apartment where I live with all my furniture and all my stuff in it.
US Immigration finds it difficult to accept that I am a Canadian citizen (and have Canadian passport) yet I've never lived in Canada nor do I have a Canadian SSN nor do I have an address in Canada nor have I filed a tax return there (my father is Canadian but I was born in UK).
I can't get any loans in the US as I don't have residency (although I don't really want a loan) and I can't buy property in the US, although I do have a US credit rating (I have a US SSN) and I managed to get a US credit card by already having an Amex when I lived abroad, and they carried the relationship over to US card (and started to add up my credit score against it).
I believe I traverse a lot of terms and conditions for things like insurance because I'm not a resident and end up being considered in the same category as an illegal immigrant - where the companies want to take their money and turn a blind eye to lack of documentation. Except that I am in the US legally and do have documentation, I'm just not a resident.
The visa I am on has no route to Green Card and so I will be in this limbo status indefinitely.