"Select a foreign-born group to see how they settled across the United States."
That's what the heading says on this page I was exploring late last night. It's an interactive map and I found it really interesting.
The map is online at The New York Times. There's a sliding scale for time period 1880 - 2000.
Basically the map shows us immigration patterns since 1880. We can see at a glance where immigrants from various countries settled, and how much of the state they inhabit. You can use the sliding scale for the time period you want, this allows you to see changes in settlement patterns. You can choose a foreign-born group (Canadian, English, etc) and see where they tended to settle.
Very interesting! One caveat - don't try this if you are on dialup as I am. I had to go to my sister-in-law's house (in civilization) to use this map!