Concise Historical Explanation: Origin of 'Americans' for US Citizens

A user is curious about the specific history behind why US citizens are called 'Americans,' especially considering other countries on the continents. They're looking for a well-researched, concise information product—like a short e-book, detailed article, or educational video—that delves into the historical, geopolitical, and linguistic reasons for this unique demonym. The goal is to provide a clear and accessible answer to a common point of historical and cultural curiosity.