William H. Rau (1855-1920) was a prominent Philadelphia photographer. He was born in Philadelphia in 1855. As a child, his older brother George operated a photography studio and, at the age of thirteen, William became an assistant to the photographer William Bell (1830-1910), who would later become his father-in-law and, in 1876, a business partner.

During the 1870s and 1880s, Rau became best known for his work photographing scenic views from around the world, beginning with a trip to the Chatham Islands and a circumnavigation of the globe following the Transit of Venus across the face of the sun with a scientific expedition. He traveled through the American West with his brother George; to Egypt, Palestine, and the Arabian Peninsula with renowned photographer Edward Livingston Wilson (1838-1903); to Mexico with the travel writer John Lawson Stoddard (1850-1931); and to sites in Europe and the Arctic as a solo practitioner. During his stays in Philadelphia, he was also a prominent portrait photographer for the city’s elite.

In 1891, Rau was commissioned by the Pennsylvania Railroad as its official photographer to document operations and scenic views along its track lines. To complete this mission, Rau traveled the railroad’s lines in a customized passenger car, fitted out with living space, a darkroom, an elevated viewing platform, a massive panoramic landscape camera, and other photographic equipment. In 1892, Rau published an illustrated pamphlet listing 312 photographs from this excursion. The photographs taken during Rau’s stint as the railroad’s photographer were also later exhibited in the Pennsylvania Railroad’s building at the World’s Columbian Exposition, which opened in Chicago in May 1893. Later that year, the Pennsylvania Railroad commissioned Rau for a second photographic campaign. In 1900, Rau published a second pamphlet featuring 497 photographs from both commissions.

In later years, Rau would also receive appointments to photograph the Louisiana Purchase Exposition in St. Louis (1904) and the Lewis and Clark Exposition in Portland (1905). By the early 1900s however, Rau’s photographic style, like that of many commercial photographers, had begun to decline in popularity in favor of more modern approaches (such as the Photo-Secession movement). Rau died at his home in Philadelphia on November 19, 1920.