What may seem logical to you is not the fact of the time.
An article in the March 27, 1861 Charleston Mercury described the early effects of secession on the business interests:
'The business men of Charleston are already beginning to reap the advantages of the independent position which the South has taken, in consequence of the refusal of the North to grant her constitutional rights.
'The results of the last few weeks have demonstrated conclusively that the commercial prosperity and political equality which THE MERCURY for years predicted, were not vain boasts. Business of all kinds has increased at an amazing pace; customers are thronging the city from all quarters of the South, and the indications are that Charleston is destined to become the commercial metropolis of the Confederate States.
'In dry goods and fancy goods the operations have been very large, and the purchasers, we are informed, are principally composed of those who used to patronize New York.
'One house alone, the business of which heretofore was chiefly confined to Georgia, has sold heavy bills to merchants from Georgia, Mississippi, Arkansas, and Texas. In shoes alone, the sales of the last two seeks have amounted to upwards of $200,000.
'In short, the prospects of Charleston never were more bright than at this season. It would be impossible to furnish at this writing details of the great increase of business which has taken place, and which is but a small part of what may be expected in the future. Suffice it to say that it is enough to stimulate the energies of our business men.
'So serious has been the effect of this rush of trade to Charleston, that Northern merchants engaged in Southern trade have circulated the report that Charleston traders have increased their prices by adding on the duties under the recent tariff charged on all good from the Northern States,,,,,in other words, that the business men of Charleston have determined to take an undue advantage of their customers.
'This is manifestly so untrue that is hardly deserving of notice, and yet it is by such means that the attempt is made to obtain Southern patronage. Not a merchant that we have visited has made any such addition to his prices. All the goods received before the tariff went into operation, are disposed of at the usual rates.
'Of course, when the merchant pays the duty, it will also be charged to the purchaser; and this is a fair business transaction. But even supposing such to be the fact, which we positively deny, would it amount to a reason why Southern merchants should buy at the North? We think not.
Clearly they would be compelled to pay a duty there, and another duty on bringing their goods across the line. where then would be the advantage?
'The end of all this will be the establishment of direct trade with Europe. A Memphis paper truly remarks:
'The establishment of the Government of the Confederate States of America, with a tariff operating upon the importations from the non-seceding States, must have the effect of driving to the seaports of the South all the trade of the cotton States, and make them great depots for foreign importation as well as the markets of purchase for the country merchants.
'The final arrangements for a line of steamer between Liverpool and this port are nearly completed now and our business community is ready to support it. This pioneer line, we confidently believe, will be followed by others in a very brief time.
'Our largest houses have looked into the future, and they are taking measures accordingly. The hardware dealer have always imported the bulk of their stock, but in the future they have determined to import more largely.
'The same remark will apply to all the other branches of trade. One of our largest drug houses has already issued a circular to its patrons on the subject, a brief extract to which is subjoined:
'As we shall hereafter import our European, Mediterranean and East India Drugs and Chemicals direct to Charleston, we omit all such from the list, and until our arrangements are completed, we will procure them on the best possible terms.
'But there is a want to be supplied. We want more houses and more capital. There is room for enterprise and money in Charleston. We feel satisfied that it will be forthcoming. The vast capital of the South will centre at this point and her energetic business men will aid in the development of our trade and commerce.
I am not familiar with USA commercial laws in 1860-61.
Was there any statutory reason why South Carolina goods and financing had to pass through Northern ports before the War?
In other words, why did South Carolina business interests wait until after secession to arrange contracts and exchange goods directly with foreign nations when it appears they could have done all of that before the War?
And why were tariffs different in different cities? Did some states and local ports charge additional tariffs?