of Darien (Isthmus of Panama). They referred to it as the Atlantic and Pacific Canal, and it was a wholly British endeavor. Projected for completion in five years, the plan was never carried out. At nearly the same time, other ideas were floated, including a canal (and/or a railroad) across Mexico's Isthmus of Tehuantepec. That did not develop, either. In 1846, the Mallarino–Bidlack Treaty, negotiated between the US and New Granada, granted the United States transit rights and the right to intervene militarily in the isthmus. In 1848, the discovery of gold in California, on the West Coast of the United States, generated renewed interest in a canal crossing between the Atlantic and Pacific oceans. William H. Aspinwall, who had won the federal subsidy to build and operate the Pacific mail steamships at around the same time, benefited from the gold discovery. Aspinwall's route included steamship legs from New York City to Panama, and from Panama to California, with an overland portage through Panama. This route with an overland leg in Panama was soon frequently traveled, as it provided one of the fastest connections between San Francisco, California, and the East Coast cities, about 40 days' transit in total. Nearly all the gold that was shipped out of California went by the fast Panama route. Several new and larger paddle steamers were soon plying this new route, including private steamship lines owned by American entrepreneur Cornelius Vanderbilt that made use of an overland route through Nicaragua, and the unfortunate SS Central America. In 1850 the United States began construction of the Panama Railroad (now called the Panama Railway) to cross the isthmus; it opened in 1855. This overland link became a vital piece of Western Hemisphere infrastructure, greatly facilitating trade. The later canal route was constructed parallel to it, as it had helped clear dense forests. An all-water route between the oceans was still the goal. In 1855 William Kennish, a Manx-born engineer working for the United States government, surveyed the isthmus and issued a report on a route for a proposed Panama Canal. His report was published as a book entitled The Practicability and Importance of a Ship Canal to Connect the Atlantic and Pacific Oceans. In 1876, Lucien Napoléon Bonaparte Wyse and his chief assistant Armand Réclus, both officers and engineers of the French Navy, explored several routes in the Darien-Atrato regions, and made proposals including the construction