It’s North
While the Northern states needed immigrants, freemen, to create and work in the tens of thousands of small farms as well as the city and town jobs (factories that employed a thousand or more workers were far more common then and many towns had factories with several hundred employees) so while there was substantial anti-immigrant politicking by the nativist movement, in general far more newcomers came in to the North.
Answer:
they were major centers for business, holding loads of money. there were thousands of people, and they were in one of the largest cities. they wanted to hit us where it hurt, and they did.
