In reply to dave o:
> which groups went in the first place, why they settled in certain locations, (e.g the Irish in NY and Boston etc) ... all this has influenced the development of the US as a country, it's ideals, culture etc up to early 20th C.
I enjoyed
The First Family by Mike Dash some years ago, and it seems to fit the bill. Quirky, readable, a minor but not insignificant chapter in the history of US immigration comprehensively mapped out.
Reviewed here:
http://www.washingtonpost.com/wp-dyn/content/article/2009/08/14/AR200908140...
Weightier by far, and by one of my favourite authors, is Samuel Morison's
The European Discovery of America; Vol 1: The Northern Voyages A.D. 500-1600. This was written years back, and I imagine things have moved on, but what a read from the Rear Admiral!