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“In 1817, Congress passed the Navigation Act, which largely resurrected the British legislation of the same name. Its provisions included a complete ban on foreign vessels from the coastal trade, enabling an already thriving merchant marine to further consolidate its position at home and abroad. One history of American shipping estimates that by 1818, the size of the coastal fleet — measured in tons — was the same as the oceangoing fleet.

The laws had unintended consequences. In the early 19th century, American shipyards and sailors could build and crew ships more cheaply and efficiently than almost any other nation, including Great Britain. Nonetheless, in the 1830s, British politicians chose not to retaliate. Instead, they opted to embrace free trade. In 1849, they stopped shielding their shipping industry from foreign competition.

This unilateral move prompted some Americans to consider doing the same. But the same year that the British steered toward free trade, the Americans discovered gold in California, prompting a massive movement of people and goods to and from the West. Though the east and west coasts weren’t actually continuous, that didn’t stop domestic shippers from invoking cabotage laws to chase out foreign competition from the new and extremely lucrative market.

But the British had the last laugh. It enjoyed a significant competitive advantage in ironworking, and in the 1850s, that country’s shipbuilders pioneered iron-hulled ships. These cheap sailing ships weighed less than American clippers and had more cargo space, and they quickly began to supplant the competition. In time, the British took the lead in building steam-powered ocean-going vessels as well. They quickly supplanted the Americans.”

https://gcaptain.com/why-the-us-embraced-the-jones-act-a-century-ago/

Right.
In, summary, by circa 1820 US ships and shippers dominated international trade, because we built better ships cheaper than anybody else.
But then began a very long, gradual slide which actually continues to this day.
The reasons were primarily technologies and economics, beginning with steam power and iron-built ships.
These rewarded ship-builders with easy access to low cost iron & steam engines.
Those were primarily Northern U.S. and even more, the Brits.
Losers were Southern ship-builders -- done in by technology and economics.
Yes, some Confederates at the time complained about it, but it takes modern Lost Causers like DiogenesLamp to make the case that the real villains in this history are his ethereal "Northeastern Power Brokers" who somehow wrote laws favoring Northern versus Southern ship-builders.

All Confederates had to do was eliminate the North's special privileges and Southern shipping would bloom again.
But in reality, when the time came, Confederates went to the Brits to get their best navy ships built.