Think what would happen if you werent allowed to go across your state's boundaries without permission. Open borders between the 50 states is one of the reasons we have had such a strong economy.
That cannot be said loudly and often enough. The explosive economic growth and evolution within the United States during the 19th century was a deliberate result of the "free trade zone" created by the complete abrogation of the power to regulate the movement of goods, services and PEOPLE by the states.
Almost as if the people who argued for the Interstate Commerce Clause had read Adam Smith.
The final abolition of free immigration only came in the 20th Century, after the Progressive revolution and the creation of the Socialist States of America. Socialist states try to regulate immigration and even movement of their populations in-country. And their economies stagnate.
Anyone can read the Federalist Papers, and the Anti-Federalist Papers, to see the arguments involved.
Here's a good place to start, the first Anti-Federalist paper, Brutus#1:
http://www.constitution.org/afp/brutus01.htmAmazing, isn't it, how the abuse of the
wording of the Interstate Commerce Clause that we all know so well was predicted right from the start. Hamilton and crowd came back defending it by predicting exactly the benefits we did see.