All of my numbers are readily available and directly sourced through google-type or AI searches.
If your inquiries produce different numbers, then the likely explanation is slightly different categories.
For one example, US 1860 cotton production is often listed as "5 million bales", which is not necessarily wrong, but I've listed it as "4.5 million standard 500 lb. bales" for purposes of calculations.
Both numbers are based on US treasury reports of 4,650,000 bales of cotton produced in 1860.
x: "What did ships that took the cotton from New Orleans (and other Southern ports) bring to those ports?"
New Orleans was the 4th largest import tariff port, after New York, Boston and Philadelphia, collecting over $2 million in import tariffs, or double every other Southern port combined.
Many ships returned to New Orleans with cargoes for sale and transport by steamboats up the Mississippi River watershed to inland ports as far away as Omaha, Minneapolis, Nashville and Pittsburgh.
However, the vast majority of ships arriving in New Orleans and other Southern ports came in ballast, meaning they had to replace normal cargos with stone, sand, iron, etc., because they had already delivered their return cargos from Europe to New York.
When the time came to pick up cotton from New Orleans, Mobile or Galveston, etc., there was relatively little those ports needed for imports.
x: "Who owned the goods that ships from Britain and Europe brought to American ports?
Surely not cotton planters or even cotton factors?"
No, of course not.
In at least 90% of cases, the cotton itself had been sold at the farmer's gate, or sometimes, Freight On Board, New Orleans (or other port) to Northern & British "factors", merchants, brokers, bank & shipping agents, etc.
Yes, on rare occasions a wealthy planter shipped his cotton to Europe on consignment, meaning he owned it until it was sold to British agents in, for example, Liverpool.
However, unlike George Washington at Mount Vernon in the 1760s, 1850s planters did not exchange their earnings from products sold in England for personal luxury goods to be delivered to their dock on the Potomac River.
Instead, consignment sales resulted in bills of exchange or credits to the planter's account which were then used to pay debts and plantation expenses.
They never resulted in planters purchasing manufactured goods for transport and sale commercially in New York, New Orleans or elsewhere.
Many thanks for your research.