1886 as contractors located at Home and Valley Streets. In the 1891 and 1892 editions of the Directory they were listed as bridge builders; their listings no longer appeared by 1900, and by 1911 William Baird had left the construction business and had begun managing a hotel. The Baird Brothers had been involved with numerous bridge projects and companies in the late nineteenth century. William Baird had worked on seven bridges crossing the Missouri River, the Merchants Bridge across the Mississippi River at St. Louis, two bridges crossing the Ohio River at Wheeling, West Virginia, the bridge carrying the Baltimore & Ohio Railroad across the Susquehanna River, and bridges at Steubenville, Ohio, and Poughkeepsie, New York. John Baird had also been involved in the construction of the Eads Bridge in St. Louis and the Cairo bridge in Memphis, and had been employed by the McCann Construction Company, the Keystone Bridge Company and American Bridge Company. This bridge was also outgrown. While the Pittsburgh City Council and the Municipal Affairs Committee of the Pittsburgh Chamber of Commerce argued for the retention and upgrading of the existing bridges, the issue was ultimately decided by the Department of War, acting under the authority of Section 18 of the Rivers and Harbors Act of March 3, 1890 (30 Stat., 1121–1153). This act empowered the Secretary of War to require the removal or alteration of any bridge which " ... is an unreasonable obstruction to the free navigation . . . on account of insufficient height, width of span, or otherwise". So, unfortunately, the War Department decreed that the numerous bridges over the Allegheny with their differing spacing of piers, main spans, and generally low clearances, were an impediment to navigation, and decreed that all bridges would have to be replaced. Although the decree was discussed in the early 1900s, and first issued in 1917, serious work did not begin till 1924. As part of the Three Sisters (Pittsburgh) project, the bridges at Sixth, Seventh, and Ninth Streets were to be demolished and replaced. The other two bridges were destroyed and scrapped, but the Cooper Bowstring trusses were moved to Coraopolis and reused. Moving the Sixth Street Bridge to Coraopolis Note: The material in this section is taken from a different HAER report. The 1892 Sixth Street Bridge (as described above, a pair of camelback Pratt trusses and the third bridge built in this location)