Washington d.c. Is misspelled over the seal
It is spelled WASIHINGTON on the front side where the seal is

Well it could be worth billions since you are the first to find one. Can you post a picture. Bills were printed from plates that printed over and over and over. There would be a great many bills like your unless its counterfit. Some were printed with the face side upside down compared to the back side but no spellin errors to date.