Joseph moved three counties west to Pittsburgh and found his first job in the retail trade with Christian Yeager.

Shea was involved with both halves of the family business — retail (Joseph Horne Co. Department Store) and wholesale (Pittsburgh Dry Goods Company).

The store was initially located on Market Street, then moved to the recently completed Mercantile Library Hall on Penn Avenue—now the site of the O'Reilly Theater—in 1871.

The flagship Horne's store at Penn Avenue and Stanwix Street in Downtown Pittsburgh originally opened on July 31, 1893,[5] and was subsequently rebuilt twice after devastating fires in 1897 and 1900.

The six-story main building and a seven-story addition dating to 1923 were both designed by Boston-based architects Peabody and Stearns.

[7] The store complex still stands and several Horne's signs remain on the building as they do at the former Pittsburgh rival Kaufmann's on Smithfield Street.

[10] The former Joseph Horne Company flagship department store is located at the corner of Penn Avenue and Stanwix Street in downtown Pittsburgh.

[12] The results were widely discussed by engineers and some of the lessons learned were incorporated into the replacement building designed by Boston-based architects Peabody and Stearns.

[13] The building was again heavily damaged by a fire in 1900 but fared better this time with the walls and steel frame surviving largely intact.

Originally a four-story office building, it was separated from the Horne store by a single house whose owner had refused to sell.

The six-story electric tree occupied a place on the corner of the building at Penn Avenue and Stanwix Street and viewers would crowd the area for a show and the lighting.

On the southwest corner of the building, two bronze plaques remain reading "Joseph Horne Co Dry Goods Importers and Retailers".

Artist Andy Warhol worked at a Horne's location in the store's display department as a summer job in 1947.

The Pittsburgh flagship store was the site of the 1987 erotic thriller, Lady Beware, which starred Diane Lane as a window designer employed there.