Trump says that he wants to take back the Panama Canal because the Canal Authority is "charging American shipping too much".
As usual with Trump's irredentist ravings, this is nonsense. But let's unpack it.
The first question you have to ask is "what American shipping"? The American merchant marine is not what it was at the end of WWII, when we had the largest merchant marine in the world.
Disclaimer: I own shares in some of these corporations, and they have made me a lot of money.
This is a list of the world's largest container ship lines.
https://en.m.wikipedia.org/wiki/List_of_largest_container_shipping_companies
You don't find an American line until you get to Matson at number 28, with 0.2% of world container capacity.
This is a list of dry bulk shipping lines.
https://www.marineinsight.com/know-more/biggest-bulk-shipping-companies/
You don't find an American dry bulk company until you get to Genco at number 10 with only 43 ships.
This is a list of tanker ship companies.
https://www.marineinsight.com/types-of-ships/top-12-tanker-shipping-companies-in-the-world/
You don't find an American tanker ship company until you get to Overseas Shipholding Group at number 12. (I own shares in them. They aren't a good performer, but they're based in Tampa Bay, so it was a sentimental purchase. Fortunately, their stock is cheap.)
There is a lot of crossover among these companies, with none of them concentrating on a single sector. They are all transnational corporations.
So again I ask, "what American shipping"?
Looking at the Canal itself, fortunately, the Canal Authority publishes statistics for Canal transits.
https://pancanal.com/en/statistics/
Selecting for laden transits by flag, the largest single flag is Liberia. No surprise there, because Liberia is the most popular open registry, so it is the flag of convenience for a lot of the world's shipping. United States flagged vessels are number 15 on that list.
Again I ask, "what American shipping"?
If you look at the graph by route, the number one route is between the US east coast and Asia.
88,428,454 of the total 210,306,847 long tons transiting the Canal are between Asia and US east coast ports, or a little over 42%. But again, considering this freight is almost all on non-US carriers, is it really "American" shipping?
Then there is the question of how much the Canal Authority is charging for transit. The Panama Canal Tariff Schedule is complex, and is available here:
https://pancanal.com/en/maritime-services/maritime-tariff/
Needless to say, shipping companies have professionals to wade through this mess.
The font of all knowledge, Google, says
"According to available information, the average cost per ton to transit the Panama Canal is not a fixed number, but varies depending on the ship's size and type, with estimates ranging around $2- $3 per ton; however, the exact cost is calculated based on a complex system considering the vessel's length, beam, and Panama Canal Universal Measurement System (PC/UMS) tonnage, making it difficult to give a single "average" cost per ton."
The Canal Authority Tariff Schedule puts the cost per container at $30-45 per twenty foot equivalent container. Considering that the cost for transporting that container will already be anywhere from $2000 to $10,000 depending on a number of factors, the $45 tariff is pocket change.
For bulk freight, the Tariff Schedule puts the cost at around $1.50 per long ton. A large bulker would pay a fee for the ship, and an additional fee for the freight. A bulker exporting, say, 60,000 tons of wheat would pay about $90,000 for the freight and another $60-100,000 for the vessel. But again, the cost of shipping dry bulk freight is already $23-27 per ton, so the additional $3-4 per ton is only a slightly larger cost.
If you're interested enough then you can calculate the full fee using the tariff estimator here:
https://www.wilhelmsen.com/tollcalculators/panama-toll-calculator/
The whole point of the Canal is that going through it saves time, fuel, and ultimately money. Yes, going through the Canal costs a lot of money. For a Panamax class container ship the tariff may be over a million dollars. But that passage may save several million dollars worth of fuel and under way time, not to mention weeks in sailing time.
Also consider that a container ship may be carrying cargo worth billions. Literally several times the value of the ship itself. At that point the cost of the Canal passage amortizes pretty quickly, in addition to the savings on fuel.
Looking at all of this, there is one important thing to consider: Ships don't have to go through the Canal. The problem is that the options are not good. One option is to go around Cape Horn, through the Straights of Magellan, which is about 8000 miles longer, and subject to violent weather. The shortest route from Asia to the US east coast is actually the Arctic Sea Route, but that is only available for a few weeks in the summer, and requires an ice strengthened hull. Another option is the Atlantic route through the Suez Canal, but because of the geopolitical situation in the middle east that can be problematic. The final option is to go around the Cape of Good Hope on the southern tip of Africa. Any way you slice it, the Panama Canal is the best option. Being good capitalists, they charge accordingly. Despite the tolls, ships still save millions over going other routes.
This doesn't touch the fact that operating and maintaining the Canal is expensive. The operating budget for the Canal is $5.7 Billion per year. That budget comes entirely from tolls.
In summary, Trump's claim that the Panama Canal Authority is overcharging American shipping is entirely irredentist nonsense from hat to boots.