>>Since I do not believe the South was in any way being deprived in 1860 of their rights to “life, liberty and the pursuit of happiness,”
The federal government had determined that the only ports of entry for European immigrants was in the north, so northern businesses had easy access to a cheap and easily-exploited labor source. There were also tariffs and laws to make it hard for southern states to ship their goods directly, requiring them to go through northern businesses.
The industrialized and commercialized north had decided that the southern states were to remain poor and agricultural and to be subservient to them for finished and imported goods.
If the south could have gotten Irish and other poor immigrants fresh off the boat to work in their fields, I’m sure that they would have sent the blacks back to Africa. After all, renting labor for slave wages is much cheaper than the cost of ownership. Because, that’s exactly what motivated the northern states to suddenly become anti-slavery after a century of making money off their import.
How so? Plenty of immigrants went through Baltimore or New Orleans (as well as New York, Philadelphia, and Boston). Shipping companies decided that New York was the most convenient port, but I don't see that the federal government had anything to do with it.
There were also tariffs and laws to make it hard for southern states to ship their goods directly, requiring them to go through northern businesses.
That was more a matter of convenience for the parties involved. New York was a major shipping and financial center. If somebody had wanted to build Charleston or Wilmington or Savannah up to the same degree they had that option. As it was, New Orleans was the second busiest port in the country by 1850 -- fourth busiest in the world, by one account.
The industrialized and commercialized north had decided that the southern states were to remain poor and agricultural and to be subservient to them for finished and imported goods.
Well, no. Southern planters wanted to remain predominantly agricultural. They didn't want heavy industry or large cities which threatened social disruption. The planters and the Southern economy were riding high in the 1850s. That's why secession was so popular. Cotton was king and the plantation economy was seen as the wave of the future.
Planters were happy to remain rich and agricultural and "subservient" to Britain and Europe for finished goods. Look up Louis Wigfall's famous "We are a peculiar people" speech: "We want no manufactures: we desire no trading, no mechanical or manufacturing classes."