|As one of the first bridges to span the Mississippi River, constructed at a time in which railroads were opening the West to settlement, the Dunleith and Dubuque Bridge was one of Iowa' s-and the country's-most historically significant early spans. Andrew Carnegie grandly characterized the structure as the most important railway bridge that had been built up to that time. And no less a personage than Abraham lincoln termed Mississippi River bridges a part of the nation's manifest destiny toward western development. Dubuque benefitted tremendously from the commerce attracted by the bridge, functioning as a regional nexus for trade throughout the late 19ih century. As trade increased, though, so did the size of the locomotives and trains crossing the bridge, and it eventually became structurally obsolete. To address this, the Dunleith and Dubuque Bridge was dismantled in pieces late in the century. This span, erected in 1871-1872 as part of a seven-span approach structure west of the main bridge, was removed and sold to Dubuque County around 1890 for use as a county-road span. Detached from the context of the original, multiple-span structure, this single span's role on a rural county road was far less momentous in its historical contribution. But as one of the last two remaining fragments of the original railroad structure in Iowa, it enjoyed a degree of significance, despite its change of setting.