Art Nouveau’s influence here was pretty much limited to decorative arts (think Tiffany lamps). Americans just had really different tastes in architecture at the time – we had Victorian houses a couple of decades before, but those were comparatively restrained, and they were built on a smaller scale than the huge apartment blocks in continental Europe.

By 1895-1900 DC was more into the clean, linear stuff (Georgian or Greek revival public buildings, Wardman houses). Even Wardman’s large public buildings (like the St. Regis) are styled after various classical revivals. IMO developers and architects in DC at the time were more into presenting the city as culturally/historically relevant than indulging trends. Even in France, Art Nouveau really only lasted for about 20 years – incredibly beautiful stuff, but a trend nonetheless.

tl;dr I’m a nerrrrrd.