It was after World War Ⅱ that the word 'capital' was generalized, and during the period before the war and for some period after the war, there were many cases where it was described as a 'chief city' (primate city) with no clear distinction made between it and normal cities.
日本で「首都」という語が一般化したのは第二次世界大戦後のことであり、戦前から戦後しばらくまでは「主都」（プライメイトシティ）を「首都」と記述する事例もおおく明確な区別はなかった。