What conflicts arose because of that expansionist policy?

“Free-soil” settlers established a rival government, and soon Kansas spiraled into civil war. Hundreds of people died in the fighting that ensued, known as “Bleeding Kansas.” A decade later, the civil war in Kansas over the expansion of slavery was followed by a national civil war over the same issue.

the constitution of the united states gave congress the absolute authority over immigration laws

pennsylvania, new hampshire, massachusetts, connecticut and rhode island .