Okay, for all who've been waiting for the answer to the recent MetroScene quiz, the first bridge built across the Potomac in or near Washington was what we now call Chain Bridge.
The picture above, taken from a print dated 1842, depicts either the fifth or sixth of eight bridges that have stood at the site, in the river gorge about two miles upstream from Georgetown.
The site obviously appealed to engineers as early as the 18th century because it was the narrowest point in the river. It also proved to be the area where high waters and ice floes were most destructive.
According to the late historian John Clagett Proctor, the first bridge at the site was built prior to 1797 to connect the port of Georgetown with the Virginia agricultural areas to the west. Two bridges that stood at the location -- from 1808 to 1810 and again in the 1830s -- were suspended from heavy chains, hence the incongruous name the bridge bears to this day.
The existing, and recently reconstructed, bridge was built in 1938 on the piers of a flood-destroyed, truss-topped structure that was erected in 1874, when nobody even had the idea people would someday be commuting across it in something called automobiles.