United States of Europe, European state, European federation, and Federal Europe are names used to refer to several similar hypothetical scenarios of the unification of Europe as a single sovereign federation of states, similar to the United States of America, both as projected by writers of speculative fiction and science fiction, and by political scientists, politicians, geographers, historians, and futurologists. At present, while the European Union (EU) is not officially a federation, various academic observers regard it as having the characteristics of a federal system.