[DiogenesLamp]

The federal government spent millions to subsidize New York City based and owned companies that took control of transoceanic trade.

The Ocean Steam Navigation Company, The United States Mail Steamship Company, The Pacific Mail Steamship Company, and the Collins Line to name a few.

Somewhere I saw some numbers regarding payments to the various Northern Shipping industries. They were quite substantial for that time period.

So the short answer as to why Southern shipping couldn't compete with Northern shipping is monopoly and subsidy.

[BroJoeK]

DiogenesLamp: "So the short answer as to why Southern shipping couldn't compete with Northern shipping is monopoly and subsidy."

Voted for and supported by majority Southern Democrat members of Congress and Southern Presidents.
Why?
Well, being politicians, there had to be some quid-pro-Quo, something equally valid in their minds to whatever such "subsidies" amounted to.

What was that quid-pro-quo?
We don't know, but since slavery was first & foremost among Southern concerns, it perhaps had to do with protecting and expanding the range of slavery in the United States.

[PeaRidge]

You are right. The figures were indeed large for the time. There were two governmental actions to underwrite the development of domestic shipping.

The cost to the Government of the first steamship subsidy venture, covering the thirteen years between 1845 and 1858, was approximately fourteen and a half million dollars.

Meeker gives the details as follows: Bremen line (1847-57) $2,000,000; Havre line (1852-57) $750,000; Collins line (1850-58) $4,500,000;Aspinwall of New York, (1848-58) $2,900,000; Astoria (1848-58) $3,750,000; Charleston Line founded by George Anson, New York (1848-58) $500,000.

Meeker, Royal, reference to his “History of Ship Subsidies,”