William Henry Aspinwall (December 16, 1807 – January 18, 1875)[1] was a prominent American businessman who was a partner in the merchant firm of Howland & Aspinwall and was a co-founder of both the Pacific Mail Steamship Company and Panama Canal Railway companies which revolutionized the migration of goods and people to the Western coast of the United States.

[3] His maternal aunt, Harriet Howland, was the third wife of Isaac's father, New York State Assemblyman James Roosevelt.

[9]: 13 His paternal grandfather, Captain John Aspinwall, was one of the most prominent shipmasters of the New York merchant marine before the American Revolutionary War.

[1][11] Another relation, Sir Algernon Aspinall, served as vice president and secretary of the West India Committee for forty years.

Also faster speed meant that the vessel could complete more voyages in a given time period, which also helped make up for the diminished cargo capacity.

The firm and its profits made Aspinwall very wealthy,[16] reportedly one of the richest men on the East Coast in the nineteenth century.

[6] In 1848, Aspinwall, along with Gardiner G. Howland and Henry Chauncey, founded the Pacific Mail Steamship Company, to provide service to California.

The project, which began in May 1850 and was later known as the Panama Canal Railway, was the first transcontinental railroad in the Americas and was built to provide a shorter and more secure path between the United States' East and West Coasts.

The tropical rain forest terrain and outbreak of malaria and cholera, rendered its five-year construction, at a cost of $8,000,000, a considerable engineering challenge, and required more than seven thousand workers drawn from "every quarter of the globe.

[26][16] He owned works by Bartolomé Esteban Murillo, Antonio da Correggio, Diego Velázquez, Bartholomeus van der Helst, Teniers, Peter Paul Rubens, Philips Wouwerman, Cuyp, Ary Scheffer, Gerard, Dow, Nicolaes Pieterszoon Berchem, Titian, Adriaen Brouwer, Gerard ter Borch, Paul Veronese, Mieris, and Leonardo da Vinci, Romney, Jean-Baptiste Greuze, and Jean-Baptiste Madou.