Before roadside vernacular, there was riverside vernacular more accurately described as "Steamboat Gothic." This style came to existence almost entirely as a product of adaptive reuse of otherwise boring structures into delightfully playful objects of desire. The Floating Palace, circa 1888, embodied the glamour and popularity of Steamboat Gothic: instant nostalgia, if there is such a thing.
In 1873, the White House was retrofitted with Victorian ornamentation, interestingly mocked by some who downplayed the changes, labeling the new style as a degrading "steamboat gothic" rather than a more civically-pleasing "pure Greek" style. Nevertheless, an impressive online gallery of images can be found at the White House Museum. In the 1950's, the White House was stripped down to it's bare structure in (what I would like to imagine) was a fit of rage by emerging Modernists. It's about time for a steamboat gothic resurgence.
Images from American Shelter, by Lester Walker.