This collection presents an instructive sequence of the development of American iron and steel bridge building. This was a pioneering time when the industry was venturing away from wood in to a new field with new materials (iron and steel), new machinery and methods of manufacture and erection. Engineers were called upon to design as well as construct bridges and develop the theory and practice of structural engineering. Bridge specifications were only adopted in 1871. Until 1876 bridge design and construction almost exclusively were controlled by companies that fabricated one particular style of bridge, for example the National Bridge and Iron Company of Boston’s adoption of the Parker truss. Many wooden truss bridge designs were adapted for use with iron. Iron bridges were mainly built between 1840 -1880 ultimately the designs were replaced by steel. The number of bridge fabricating companies exploded during the second half of the 19th century doubling every decade. In 1850 there were only 15 workshops and by 1900 more than 190 bridge fabricators were operating in the United States due to the expansion of the railroads following the Civil War. The U.S. bridge fabricating shops had skilled mechanics that assembled the bridge parts st the fabricating shop to ensure proper size before shipment for erection by bridge builders at the site. The parts were marked so that the men in the field could quickly reassemble the parts into a bridge on site. The technique of prefabricating and preassembling all the parts to guarantee an exact fit and then securing the members with pins (Lehigh’s Archives has an example of one such pin from the Brooklyn Bridge in its collection) became known as the “American plan.” It appears from the Liscom Family collection of ephemera that some of the Liscom family especially L. F. Liscom worked in the field as a bridge builder or in the bridge fabricating shop planning bridges. One family member was an inventor (Levi Liscom Patent No. 76,212, 1868 for a bridge of corbelled timber beams extending to mid-span support and stiffened by a truss). From the collection of business correspondence and business cards, it is evident that the Liscom family worked for a range of bridge companies. Among them was the Solid Lever Bridge Company with C. H. Parker as engineer (designed the Parker Truss). Its successor, the National Bridge and Iron Works, collapsed in 1876. Its engineer, D(avid) H. Andrews (1844-1921), bought their equipment and materials and began the Boston Bridge Works. The Boston Bridge Works manufactured iron work for subways and bridges for railroads. It was the largest bridge shop manufacturing iron bridge members in Boston from 1894 to 1903 employing 175 men. For twenty years Boston Bridge Works with Andrews as owner and designer built most of the railway and highway bridges of New England and other parts of the country along with the first steel building in Boston. The Liscom correspondence indicates that L. F(rank) Liscom was one of the 175 men employed by the Works and possibly one of the Andrews design engineers. Other companies where L. F. Liscom possibly was affiliated - the Eastern Bridge and Structural Company and the United Construction Company, so he probably was one of many itinerant entrepreneurs busy in the 19th century bridge building trade. Engineers at that time were called upon to design as well as construct and develop the theory and practice of structural engineering.