Until we stumbled upon this marker on the campus of George Washington University I had no idea that there had ever been an American Meridian!
By 1848 we had our own Observatory, thank you very much, and the American Meridian runs smack through it. Never mind that it is less logical to have your measurements based on a longitude of 77.2.48 instead of a nice round Zero.
So for about 40 years we measured our state boundries, in such places where rivers did not mark them, based on the American Meridian.
Like all tourists to Greenwich I have stood with one foot in East and one in West. The obsolete American Meridian does not have the same feel to it, but what the heck.