On April 1, 1845, along with Henry Wells and Daniel Dunning, Fargo organized the Western Express which ran from Buffalo to Cincinnati, St. Louis, Chicago and intermediate points, under the name of Wells & Co. At that time, there were no railroad facilities west of Buffalo, and Fargo, who had charge of the business, made use of steamboats and wagons.

In 1845, Daniel Dunning withdrew from the company and in 1846, Henry Wells sold out his interest in this concern to William A. Livingston, who became Fargo's partner in Livingston, Fargo & Company.
 In 1850, three competing express companies: Wells & Company (Henry Wells), Livingston, Fargo & Company (Fargo and William A. Livingston), and Wells, Butterfield & Company, the successor earlier in 1850 of Butterfield, Wasson & Company (John Warren Butterfield), were consolidated and became the American Express Company, with Wells as President and Fargo as Secretary.

In 1866, upon the resignation of Henry Wells and American Express' merger with the Merchants Union Express Company, Fargo was elected President of the American Express Company.
He was the company's president until his death in 1881, at which point his brother, J. C. Fargo, assumed the presidency, holding the post until 1914.
On April 1, 1845, along with Henry Wells and Daniel Dunning, Fargo organized the Western Express which ran from Buffalo to Cincinnati, St. Louis, Chicago and intermediate points, under the name of Wells & Co. At that time, there were no railroad facilities west of Buffalo, and Fargo, who had charge of the business, made use of steamboats and wagons.
In 1845, Daniel Dunning withdrew from the company and in 1846, Henry Wells sold out his interest in this concern to William A. Livingston, who became Fargo's partner in Livingston, Fargo & Company.  In 1850, three competing express companies: Wells & Company (Henry Wells), Livingston, Fargo & Company (Fargo and William A. Livingston), and Wells, Butterfield & Company, the successor earlier in 1850 of Butterfield, Wasson & Company (John Warren Butterfield), were consolidated and became the American Express Company, with Wells as President and Fargo as Secretary.
In 1866, upon the resignation of Henry Wells and American Express' merger with the Merchants Union Express Company, Fargo was elected President of the American Express Company. He was the company's president until his death in 1881, at which point his brother, J. C. Fargo, assumed the presidency, holding the post until 1914.
William Fargo