Isthmus of Panama
The U.S. Post Office at Panama was established in 1826. That was the first, officially recorded, use of the name "Panama". The traditional story is that Panama got its name from someone who had been across the Isthmus of Panama, and said local rock formations reminded him of Panama's rocks. It is possible that this person was Moses Cushman Marsh, who operated a trading company in Panama, and was Panama's first postmaster. He had previously had a business in Cuba, and he may have been across the Isthmus of Panama.